This study investigated the effects of ATP-sensitive potassium channels on the expression of P21, P27 and leptin. The expression of receptor of ATP-sensitive potassium channels (sulphonylurea receptor, SUR) mRNA in ...This study investigated the effects of ATP-sensitive potassium channels on the expression of P21, P27 and leptin. The expression of receptor of ATP-sensitive potassium channels (sulphonylurea receptor, SUR) mRNA in the preadipocytes and leptin mRNA was detected by PCR after rat preadipocytes were treated with the opener (diazoxide) or inhibitor (glibenclamide) of ATP-sensitive potassium channels during the process of inducing differentiation. The expression of P21 and P27 in preadipocytes treated with diazoxide or glibenclamide was assayed by Western blot. The results showed that the expression of SUR2, not SUR1 was detected in adipose tissue, preadipocytes and adipocytes. Alter treatment of preadipocytes with diazoxide, the expression levels of P21 and P27 were obviously higher than glibenclamide-treat ed group those in control group, but the were lower than those in control expression levels of P21 and P27 in group. During the process of inducing differentiation, the expression of leptin mRNA in preadipocytes treated with diazoxide was increased greatly, but the expression of leptin mRNA in glibenclamide-treated group decreased obviously. It was concluded that ATP-sensitive potassium channels might be involved in the proliferation and differentiation of rat preadipocytes by changing the expression of P21, P27 and leptin.展开更多
Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were...Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.展开更多
Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmo...Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance,reverse pulmonary vascular remodeling,and thereby improving right ventricular function.Iptakalim,a lipophilic para-amino compound with a low molecular weight,has been demonstrated to be a new selective ATP-sensitive potassium(K ATP) channel opener via pharmacological,electrophysiological,biochemical studies,and receptor binding tests.In hypoxia-induced animal models,iptakalim decreases the elevated mean pressure in pulmonary arteries,and attenuates remodeling in the right ventricle,pulmonary arteries and airways.Furthermore,iptakalim has selective antihypertensive effects,selective vasorelaxation effects on smaller arteries,and protective effects on endothelial cells,but no effects on the central nervous,respiratory,digestive or endocrine systems at therapeutic dose.Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1,reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells.Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials,it can be a potential candidate of HPH in the future.展开更多
AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cell...AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique.The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread.Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro.Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel.Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.RESULTS:We found that both CBS and CSE were expressed in the cul tured smooth muscle cel ls from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations.In addition,nicardipine and aminooxyacetic acid(AOAA),a CBS inhibitor,reduced the tension,whereas Nω-nitro-L-arginine methyl ester,a nonspecific nitric oxide synthase,increased the tension.The AOAA-induced relaxation was significantly recovered by H2S,and the Na HS-induced increase in tonic contraction was blocked by 5 mmol/L4-aminopyridine and 1μmol/L nicardipine.Na HS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents.Moreover,Na HS increased L-type Ca2+currents and caused an elevation in intracellular calcium([Ca2+]i).CONCLUSION:These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice.The excitatory effect is mediated by voltagedependent potassium and L-type calcium channels.展开更多
The influence of hypoxia on the activity of voltage-gated potassium channel in pulmonary artery smooth muscle cells (PASMCs) of rats and its roles in the pathogenesis of chronic pulmonary heart disease were investig...The influence of hypoxia on the activity of voltage-gated potassium channel in pulmonary artery smooth muscle cells (PASMCs) of rats and its roles in the pathogenesis of chronic pulmonary heart disease were investigated. Eighty male Sprague-Dawley rats were randomly allocated into control group (n=10), acute hypoxic group (n=10), and chronic hypoxic groups (n=60). The chronic hypoxic groups were randomly divided into 6 subgroups (n=10 each) according to the chronic hypoxic periods. The rats in the control group were kept in room air and those in acute hypoxic group in hypoxia envi- ronmental chamber for 8 h. The rats in chronic hypoxic subgroups were kept in hypoxia environmental chamber for 8 h per day for 5, 10, 15, 20, 25, and 30 days, respectively. The mean pulmonary arterial pressure (mPAP), right ventricular hypertrophy index (RVHI), and the current of voltage-gated potas- sium channel (IK) in PASMCs were measured. Results showed that both acute and chronic hypoxia could decrease the IK in PASMCs of rats and the I-V relationship downward shifted to the right. And the peak Ir density at +60mV decreased with prolongation of hypoxia exposure. No significant difference was noted in the density oflK (at +60 mV) and I-V relationship between control group and chronic hy- poxic subgroup exposed to hypoxia for 5 days (P〉0.05), but there was a significant difference between control group and chronic hypoxic subgroup exposed to hypoxia for 10 days (P〈0.05). Significant dif- ferences were noted in the IK density (at +60 mV) and I-V relationships between control group and chronic hypoxic subgroups exposed to hypoxia for 20 days and 30 days (P〈0.01). Compared with con- trol rats, the mPAP and RVHI were significantly increased after chronic exposure to hypoxia for 10 days (P〈0.05), which were further increased with prolongation of hypoxia exposure, and there were signifi- cant differences between control group and chronic hypoxic subgroups exposed to hypoxia for 20 days and 30 days (P〈0.01). Both the mPAP and the RVHI were negatively correlated with the density OflK (r---0.89769 and -0.94476, respectively, both P〈0.01). It is concluded that exposure to hypoxia may cause decreased activity of voltage-gated potassium channel, leading to hypoxia pulmonary vasocon- striction (HPV). Sustained HPV may result in chronic pulmonary hypertension, even chronic pulmonary heart disease, contributing to the pathogenesis of chronic pulmonary heart disease.展开更多
Catilan extracted from Leiurus quinquestriatus is a specific ion channel blocker.It can specifically bind chloride channels of glioma cells and kill these tumor cells.The questions remain as to whether antigliomatin,t...Catilan extracted from Leiurus quinquestriatus is a specific ion channel blocker.It can specifically bind chloride channels of glioma cells and kill these tumor cells.The questions remain as to whether antigliomatin,the extract from scorpion venom of Buthus martensii Karsch in China,can inhibit glioma growth,and whether this inhibition is correlated with ion channels of tumor cells.The present study treated rat C6 glioma cells with 0.8,1.2,and 1.6 μg/mL antigliomatin for 20 hours.Whole-cell patch clamp technique showed that antigliomatin delayed rectifier potassium channels of C6 glioma cells.Antigliomatin inhibited tumor growth,which could potentially involve potassium channels of tumor cells.展开更多
Ion channels modulate cellular excitability by regulating ionic fluxes across biological membranes.Pathogenic mutations in ion channel genes give rise to epileptic disorders that are among the most frequent neurologic...Ion channels modulate cellular excitability by regulating ionic fluxes across biological membranes.Pathogenic mutations in ion channel genes give rise to epileptic disorders that are among the most frequent neurological diseases affecting millions of individuals worldwide.Epilepsies are trigge red by an imbalance between excitatory and inhibitory conductances.However,pathogenic mutations in the same allele can give rise to loss-of-function and/or gain-of-function va riants,all able to trigger epilepsy.Furthermore,certain alleles are associated with brain malformations even in the absence of a clear electrical phenotype.This body of evidence argues that the underlying epileptogenic mechanisms of ion channels are more diverse than originally thought.Studies focusing on ion channels in prenatal cortical development have shed light on this apparent paradox.The picture that emerges is that ion channels play crucial roles in landmark neurodevelopmental processes,including neuronal migration,neurite outgrowth,and synapse formation.Thus,pathogenic channel mutants can not only cause epileptic disorders by alte ring excitability,but further,by inducing morphological and synaptic abnormalities that are initiated during neocortex formation and may persist into the adult brain.展开更多
The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were in...The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.展开更多
Astrocytic Kir4.1 channels and spatial potassium buffering:Astrocytes play a crucial role in maintaining the structural and functional integrity of the brain,which includes formation of the blood-brain barrier,mainte...Astrocytic Kir4.1 channels and spatial potassium buffering:Astrocytes play a crucial role in maintaining the structural and functional integrity of the brain,which includes formation of the blood-brain barrier,maintenance of water and ion homeostasis,metabolism of neurotransmitters and secretion of various neuroactive molecules.展开更多
The effects of levobunolol hydrochlorid (Bun) on the type L calciumchannel currents (Ica) and delayed rectifier potassium channel currents (Ik) in isolated ventricular myocytes of guinea pig were studied by using patc...The effects of levobunolol hydrochlorid (Bun) on the type L calciumchannel currents (Ica) and delayed rectifier potassium channel currents (Ik) in isolated ventricular myocytes of guinea pig were studied by using patch clamp wholecell recording techniques. The results were showed that: 1) Bun caused a dosedependent decrease in Ica and a dose-dependent increase in Ik of the ventricular myocytes.The threshold concentrations of Bun for Ica and Ik were 10-8 mol/L and10-7 mol/L respectively. The maximum effective concentration of Bun for both Ica and Ik was 3 × 10-5 mol/L, and half-maximal concentration was 3 × 10-6 mol/L;2 ) Ik was blocked by 2× 10-6mol/L tetraethylammonium (TEA). A concentration of 3 × 10-6 mol/L Bun showed a decreasing effect on the Ica as revealed by the current-voltage relationship curve, i. e., Bun caused an elevation of the curve; 3)When Ica was blocked by 2 × 10-6 mol/L Isoptin (Verapamil), at a concentrationof 3 × 106- mol/L Bun showed an increasing effect on Ik and the effect could be blocked by TEA. The above-mentioned results indicated that Bun had an inhibito-ry effect on Ica and a fascilitatory effect on Ik The results suggested that themolecular mechanisms of antihypertensive, heart rate slowing and β-receptorblocking effects of Bun might be due to decrease of Ica and increase of Ik.展开更多
BACKGROUND ATP sensitive K+(K_(ATP))channels are ubiquitously distributed in various of cells and tissues,including the liver.They play a role in the pathogenesis of myocardial and liver ischemia.AIM To evaluate the r...BACKGROUND ATP sensitive K+(K_(ATP))channels are ubiquitously distributed in various of cells and tissues,including the liver.They play a role in the pathogenesis of myocardial and liver ischemia.AIM To evaluate the radiation-induced changes in the expression of K_(ATP)channel subunits in the mouse liver to understand the potential role of K_(ATP)channels in radiation injury.METHODS Adult C57BL/6 mice were randomly exposed toγ-rays at 0 Gy(control,n=2),0.2 Gy(n=6),1 Gy(n=6),or 5 Gy(n=6).The livers were removed 3 and 24 h after radiation exposure.Hematoxylin and eosin staining was used for morphological observation;immunohistochemical staining was applied to determine the expression of K_(ATP)channel subunits in the liver tissue.RESULTS Compared with the control group,the livers exposed to 0.2 Gyγ-ray showed an initial increase in the expression of Kir6.1 at 3 h,followed by recovery at 24 h after exposure.Exposure to a high dose of 5.0 Gy resulted in decreased expression of Kir6.1 and increased expression of SUR2B at 24 h.However,the expression of Kir6.2,SUR1,or SUR2A had no remarkable changes at 3 and 24 h after exposure to any of these doses.CONCLUSION The expression levels of Kir6.1 and SUR2B in mouse liver changed differently in response to different radiation doses,suggesting a potential role for them in radiation-induced liver injury.展开更多
There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generaliz...There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generalized ischemia and hypoxia. Although widely distributed, the physiological differences among BK channels which results from posttranslational modification (alternative splicing) and co-assembly with auxiliary modulatory subunits (<em>β</em><sub>1-4</sub> and <em>γ</em><sub>1-4</sub>), bestows localized differences in subunit composition, distribution, 2<sup>nd</sup>-messenger coupling, and pharmacologic properties. Due to the ubiquitous nature of BK channels and the multiplicity of subtypes, they have many potential therapeutic applications in the maintenance of oxygen homeostasis, cerebro- and cardio-protection, and stimulation of respiration in response to drug-induced respiratory depression. BK channels may also offer other potentially broad and underrecognized promising targets for novel pharmaceutical development.展开更多
In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine tr...In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease in PC12 cell viability induced by amyloid-β peptide (25-35). Diazoxide protected PC12 cells against amyloid-β peptide (25-35)-induced increases in mitochondrial membrane potential and intracellular reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nw-nitro-L-arginine, also protected PC12 cells from amyloid-β peptide (25-35)-induced increases in both mitochondrial membrane potential and intracellular reactive oxygen species levels. However, the H202-degrading enzyme catalase could not reverse the amyloid-β peptide (25-35)-induced increase in intracellular reactive oxygen species. A 24-hour exposure to amyloid-13 peptide (25-35) did not result in apoptosis or necrosis, suggesting that the increases in both mitochondrial membrane potential and reactive oxygen species levels preceded cell death. The data suggest that amyloid-β peptide (25-35) cytotoxicity is associated with adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β peptide (25-35).展开更多
Objective: To investigate the role of large Ca^2+-activated, delayed-rectifier and ATP-sensitive potassium channel in regulating the relaxation induced by nitric oxide (NO) in normal and passively sensitized human...Objective: To investigate the role of large Ca^2+-activated, delayed-rectifier and ATP-sensitive potassium channel in regulating the relaxation induced by nitric oxide (NO) in normal and passively sensitized human airway smooth muscle (HASM) with serum from asthmatic patients. Methods: The effects of NO or/and potassium channel blockers on the tensions of normal and passively sensitized HASM were measured by using nitric oxide donor and potassium blockers, with the isometric tension recording technique. Results: Showed that(1)In the control group and passively sensitized group, Kv blocker(4-AP) cause concentration-dependent augmentation in the contraction induced by histamine ( 1 ×10^-4 mol/L ), (P 〈 0.05), but Glib ( 1 × 10^-2 mol/L ) and TEA (1×10^-4 mol/L) have no significant effects on the contraction induced by histamine (1×10^-4 mol/L). The maximum tension induced by histamine in passively sensitized group is higher than that in the control group (P 〈 0.05). (2) NO-donor Sodium Nitroprusside (SNP) bring about significant relaxation in normal and passively sensitized HASM rings (P 〈 0.05). Relaxations of passively sensitized airway rings [ (29.4 ± 3.3)% ] were significant less than those of normal HASM rings [ (44.1 ± 10.2)% ], (P 〈 0.05).(3) Glib(1×10^-2 mol/L)have no significant effect on the relaxations induced by SNP(1×10^-4 mol/L). 4-AP(1×10^-2 mol/L) inhibited relaxation induced by SNP (1×10^-4 mol/L), (P 〈 0.01). TEA (1×10^-3 tool/L) inhibited relaxation induced by SNP (1×10^-4 mol/L) (P 〈 0.05), and the inhibiting effect in passively sensitized HASM rings were significant less than in normal HASM, (P 〈 0.05). Conclusion: It was concluded that SNP(NO-donor) relaxed the contraction of HASM partly via BKca channel opening. In passively sensitized HASM in vitro, the relaxation of SNP decreased compared with control group, which might be associated with the down-regulating activity of BKca in passively sensitized HASM.展开更多
BACKGROUND ATP-sensitive K^+(KATP)channels were originally found in cardiac myocytes by Noma in 1983.KATP channels were formed by potassium ion-passing poreforming subunits(Kir6.1,Kir6.2)and regulatory subunits SUR1,S...BACKGROUND ATP-sensitive K^+(KATP)channels were originally found in cardiac myocytes by Noma in 1983.KATP channels were formed by potassium ion-passing poreforming subunits(Kir6.1,Kir6.2)and regulatory subunits SUR1,SU2A and SUR2B.A number of cells and tissues have been revealed to contain these channels including hepatocytes,but detailed localization of these subunits in different types of liver cells was still uncertain.AIM To investigate the expression of KATP channel subunits in rat liver and their localization in different cells of the liver.METHODS Rabbit anti-rat SUR1 peptide antibody was raised and purified by antigen immunoaffinity column chromatography.Four of Sprague-Dawley rats were used for liver protein extraction for immunoblot analysis,seven of them were used for immunohistochemistry both for the ABC method and immunofluorescence staining.Four of Wistar rats were used for the isolation of hepatic stellate cells(HSCs)and Kupffer cells for both primary culture and immunocytochemistry.RESULTS Immunoblot analysis showed that the five kinds of KATP channel subunits,i.e.Kir6.1,Kir6.2,SUR1,SUR2A,and SUR2B,were detected in liver.Immunohistochemical staining showed that Kir6.1 and Kir6.2 were weakly to moderately expressed in parenchymal cells and sinusoidal lining cells,while SUR1,SUR2A,and SUR2B were mainly localized to sinusoidal lining cells,such as HSCs,Kupffer cells,and sinusoidal endothelial cells.Immunoreactivity for SUR2A and SUR2B was expressed in the hepatocyte membrane.Double immunofluorescence staining further showed that the pore-forming subunits Kir6.1 and/or Kir6.2 colocalized with GFAP in rat liver sections and primary cultured HSCs.These KATP channel subunits also colocalized with CD68 in liver sections and primary cultured Kupffer cells.The SUR subunits colocalized with GFAP in liver sections and colocalized with CD68 both in liver sections and primary cultured Kupffer cells.In addition,five KATP channel subunits colocalized with SE-1 in sinusoidal endothelial cells.CONCLUSION Observations from the present study indicated that KATP channel subunits expressed in rat liver and the diversity of KATP channel subunit composition might form different types of KATP channels.This is applicable to hepatocytes,HSCs,various types of Kupffer cells and sinusoidal endothelial cells.展开更多
Objectives Ischemia induced arrhythmia(ventricular tachycardia/ventricular fibrillation) is one of the major causes of death.Potassium channels change are likely to be responsible for the ischemia-related arrhythmias....Objectives Ischemia induced arrhythmia(ventricular tachycardia/ventricular fibrillation) is one of the major causes of death.Potassium channels change are likely to be responsible for the ischemia-related arrhythmias.Cardiac potassium current is the major outward current involved in cardiac repolarization.The properties of potassium channels have been intensively studied.Here,we investigated the association between ischemia induced arrhythmia and potassium channels genetic variations.Methods 23 patients with ventricular tachycardia/ventricular fibrillation induced by ischemia were selected as objects.5ML peripheral blood were taken from each person,from which DNA was extracted us- ing a standard enzymatic phenol-chloroform method.Candidate genes(HERG、KCNJ2、KCNQ1、Mink、Mirp1、Kir2.1、KV4.3、Kir3.1、KV1.5、Kir6.1、Kir6.2、Kir2.1) Were screened for potassium channels gene mutations with direct sequencing methods.Results Here 4 potassium channels gene mutations have been discovered.In the gene coding for the ATP-sensitive K^+ channels subunit Kir6.2,there is a change from valine to isoleucine at the position of 326(V326I).At the position 448,arginine substitutes proline(P448R) in the KC-NQ1 gene.In the gene KCNJ2 two mutations have been found(P156L,Q193H).Conclusions This study implicated that there is a high relationship between ischemia induced arrhythmia and the mutation of potassium channels.In order to identify the precisely relationship there is need functional analysis.展开更多
Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferatio...Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells(vascular smooth muscle cells, VSMCs)were observed by the means of computerised image analysis and MTT method respectively. Furthermore, whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they was more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control).TEA(blocker of Ca2+ activated potassium channels)increased MTT A490 nm value of VSMCs from femoral vein in a dose dependent manner(P<0.05, n=8). KCa current density was significantly attenuated in VSMCs from autogenous vein grafts (1-4) week after transplantation(P<0.05, n=5).Conclusion: KCa is inhibited in autogenous vein graft, which account for vasospasm and intimal proliferation.展开更多
Uging diet control method to feed the weaning male Wistar rats with selenium and iodine deficiency Keshan endemic area food for 8 weeks to set up animal model. Singal channel recortling in cell attached model was used...Uging diet control method to feed the weaning male Wistar rats with selenium and iodine deficiency Keshan endemic area food for 8 weeks to set up animal model. Singal channel recortling in cell attached model was used to measure cardiac cell membrane potassium channel conductances. which coincide with the cardiac cell membrane potassium channel conductances in normal Wistar rats.The potassium channel conductance on selenlum and lodine cleficiency rat cardiac cell membrane is showing current-voltage increasing lineally in the range of clamping volatge 0±30 mV with channel conductance of 43.4 pS. The channel current does not increase depending on the clamping voltage that is showing the rectifying characteristic and the channel current amplitude can be augmented by added KIOa 5 mmol/L in bath solution. A kind of inward rectiyfing potassium channel activity was recorded, but this channel activity disappeared affer lasting 6~ 10 minutes only. Then an inward rectifying potassium channel with the conductance of 11. 2 PS was activated by KIOa 5 mmol/L, introduced to bath solution. Both conductances are less than that of normal Wistar rats.展开更多
文摘This study investigated the effects of ATP-sensitive potassium channels on the expression of P21, P27 and leptin. The expression of receptor of ATP-sensitive potassium channels (sulphonylurea receptor, SUR) mRNA in the preadipocytes and leptin mRNA was detected by PCR after rat preadipocytes were treated with the opener (diazoxide) or inhibitor (glibenclamide) of ATP-sensitive potassium channels during the process of inducing differentiation. The expression of P21 and P27 in preadipocytes treated with diazoxide or glibenclamide was assayed by Western blot. The results showed that the expression of SUR2, not SUR1 was detected in adipose tissue, preadipocytes and adipocytes. Alter treatment of preadipocytes with diazoxide, the expression levels of P21 and P27 were obviously higher than glibenclamide-treat ed group those in control group, but the were lower than those in control expression levels of P21 and P27 in group. During the process of inducing differentiation, the expression of leptin mRNA in preadipocytes treated with diazoxide was increased greatly, but the expression of leptin mRNA in glibenclamide-treated group decreased obviously. It was concluded that ATP-sensitive potassium channels might be involved in the proliferation and differentiation of rat preadipocytes by changing the expression of P21, P27 and leptin.
文摘Objectives To investigate the effect of Gαq/11 signaling pathway and ATP-sensitive potassium channel ( KATP channel ) on ischemic preconditioning (IPC) protection in rat hearts. Methods Two series of experiments were performed in Wistar rat hearts. In the first series of experiment, ischemic preconditioning was induced by left anterior descending occlusion (three, 5 min episodes separated by 5 min of reperfusion), ischemia-reperfusion injury was induced by 30 min coronary artery occlusion followed by 90 min reperfusion. Hemodynamics, infarct size and scores of ventricular arrhythmias were measured. The expression of Gαq/11 protein in the heart was measured by Western blot analysis in the second series. Results Ischemic preconditioning rats showed decreased infarct size and scores of ventricular arrhythmia vs non-IP control rats. The effect of IPC was significantly attenuated by glibenclamide (1 mg/kg, ip), a nonselective KATP channel inhibitor. IPC caused a significant increase in the expression of Gαq/11 protein. Conclusions Activations of Gαq/11 signal pathway and KATP channel played significant roles in the classical cardioprotection of ischemic precon-ditioning rat heart and might be an important mechanism of signal transduction pathway during the ischemic preconditioning.
基金supported by National Major Scientific and Technological Special Project for"Significant New Drugs Development"(2011ZX09302-003-02)
文摘Hypoxic pulmonary hypertension(HPH) is a syndrome characterized by the increase of pulmonary vascular tone and the structural remodeling of peripheral pulmonary arteries.The aim of specific therapies for hypoxic pulmonary hypertension is to reduce pulmonary vascular resistance,reverse pulmonary vascular remodeling,and thereby improving right ventricular function.Iptakalim,a lipophilic para-amino compound with a low molecular weight,has been demonstrated to be a new selective ATP-sensitive potassium(K ATP) channel opener via pharmacological,electrophysiological,biochemical studies,and receptor binding tests.In hypoxia-induced animal models,iptakalim decreases the elevated mean pressure in pulmonary arteries,and attenuates remodeling in the right ventricle,pulmonary arteries and airways.Furthermore,iptakalim has selective antihypertensive effects,selective vasorelaxation effects on smaller arteries,and protective effects on endothelial cells,but no effects on the central nervous,respiratory,digestive or endocrine systems at therapeutic dose.Our previous studies demonstrated that iptakalim inhibited the effects of endothelin-1,reduced the intracellular calcium concentration and inhibited the proliferation of pulmonary artery smooth muscle cells.Since iptakalim has been shown safe and effective in both experimental animal models and phase I clinical trials,it can be a potential candidate of HPH in the future.
基金Supported by National Natural Science Foundation of China,No.31171107,No.31071011 and No.31271236
文摘AIM:To investigate the effect of hydrogen sulfide(H2S)on smooth muscle motility in the gastric fundus.METHODS:The expression of cystathionineβ-synthase(CBS)and cystathionineγ-lyase(CSE)in cultured smooth muscle cells from the gastric fundus was examined by the immunocytochemistry technique.The tension of the gastric fundus smooth muscle was recorded by an isometric force transducer under the condition of isometric contraction with each end of the smooth muscle strip tied with a silk thread.Intracellular recording was used to identify whether hydrogen sulfide affects the resting membrane potential of the gastric fundus in vitro.Cells were freshly separated from the gastric fundus of mice using a variety of enzyme digestion methods and whole-cell patch-clamp technique was used to find the effects of hydrogen sulfide on voltage-dependent potassium channel and calcium channel.Calcium imaging with fura-3AM loading was used to investigate the mechanism by which hydrogen sulfide regulates gastric fundus motility in cultured smooth muscle cells.RESULTS:We found that both CBS and CSE were expressed in the cul tured smooth muscle cel ls from the gastric fundus and that H2S increased the smooth muscle tension of the gastric fundus in mice at low concentrations.In addition,nicardipine and aminooxyacetic acid(AOAA),a CBS inhibitor,reduced the tension,whereas Nω-nitro-L-arginine methyl ester,a nonspecific nitric oxide synthase,increased the tension.The AOAA-induced relaxation was significantly recovered by H2S,and the Na HS-induced increase in tonic contraction was blocked by 5 mmol/L4-aminopyridine and 1μmol/L nicardipine.Na HS significantly depolarized the membrane potential and inhibited the voltage-dependent potassium currents.Moreover,Na HS increased L-type Ca2+currents and caused an elevation in intracellular calcium([Ca2+]i).CONCLUSION:These findings suggest that H2S may be an excitatory modulator in the gastric fundus in mice.The excitatory effect is mediated by voltagedependent potassium and L-type calcium channels.
文摘The influence of hypoxia on the activity of voltage-gated potassium channel in pulmonary artery smooth muscle cells (PASMCs) of rats and its roles in the pathogenesis of chronic pulmonary heart disease were investigated. Eighty male Sprague-Dawley rats were randomly allocated into control group (n=10), acute hypoxic group (n=10), and chronic hypoxic groups (n=60). The chronic hypoxic groups were randomly divided into 6 subgroups (n=10 each) according to the chronic hypoxic periods. The rats in the control group were kept in room air and those in acute hypoxic group in hypoxia envi- ronmental chamber for 8 h. The rats in chronic hypoxic subgroups were kept in hypoxia environmental chamber for 8 h per day for 5, 10, 15, 20, 25, and 30 days, respectively. The mean pulmonary arterial pressure (mPAP), right ventricular hypertrophy index (RVHI), and the current of voltage-gated potas- sium channel (IK) in PASMCs were measured. Results showed that both acute and chronic hypoxia could decrease the IK in PASMCs of rats and the I-V relationship downward shifted to the right. And the peak Ir density at +60mV decreased with prolongation of hypoxia exposure. No significant difference was noted in the density oflK (at +60 mV) and I-V relationship between control group and chronic hy- poxic subgroup exposed to hypoxia for 5 days (P〉0.05), but there was a significant difference between control group and chronic hypoxic subgroup exposed to hypoxia for 10 days (P〈0.05). Significant dif- ferences were noted in the IK density (at +60 mV) and I-V relationships between control group and chronic hypoxic subgroups exposed to hypoxia for 20 days and 30 days (P〈0.01). Compared with con- trol rats, the mPAP and RVHI were significantly increased after chronic exposure to hypoxia for 10 days (P〈0.05), which were further increased with prolongation of hypoxia exposure, and there were signifi- cant differences between control group and chronic hypoxic subgroups exposed to hypoxia for 20 days and 30 days (P〈0.01). Both the mPAP and the RVHI were negatively correlated with the density OflK (r---0.89769 and -0.94476, respectively, both P〈0.01). It is concluded that exposure to hypoxia may cause decreased activity of voltage-gated potassium channel, leading to hypoxia pulmonary vasocon- striction (HPV). Sustained HPV may result in chronic pulmonary hypertension, even chronic pulmonary heart disease, contributing to the pathogenesis of chronic pulmonary heart disease.
基金the Science and Technology Development Program of Jilin Province, No. 20050407-6
文摘Catilan extracted from Leiurus quinquestriatus is a specific ion channel blocker.It can specifically bind chloride channels of glioma cells and kill these tumor cells.The questions remain as to whether antigliomatin,the extract from scorpion venom of Buthus martensii Karsch in China,can inhibit glioma growth,and whether this inhibition is correlated with ion channels of tumor cells.The present study treated rat C6 glioma cells with 0.8,1.2,and 1.6 μg/mL antigliomatin for 20 hours.Whole-cell patch clamp technique showed that antigliomatin delayed rectifier potassium channels of C6 glioma cells.Antigliomatin inhibited tumor growth,which could potentially involve potassium channels of tumor cells.
基金NJ Governor’s Council for Medical Research and Treatment of Autism predoctoral fellowship (CAUT23AFP015) to ABNational Science Foundation grant (2030348) to FS。
文摘Ion channels modulate cellular excitability by regulating ionic fluxes across biological membranes.Pathogenic mutations in ion channel genes give rise to epileptic disorders that are among the most frequent neurological diseases affecting millions of individuals worldwide.Epilepsies are trigge red by an imbalance between excitatory and inhibitory conductances.However,pathogenic mutations in the same allele can give rise to loss-of-function and/or gain-of-function va riants,all able to trigger epilepsy.Furthermore,certain alleles are associated with brain malformations even in the absence of a clear electrical phenotype.This body of evidence argues that the underlying epileptogenic mechanisms of ion channels are more diverse than originally thought.Studies focusing on ion channels in prenatal cortical development have shed light on this apparent paradox.The picture that emerges is that ion channels play crucial roles in landmark neurodevelopmental processes,including neuronal migration,neurite outgrowth,and synapse formation.Thus,pathogenic channel mutants can not only cause epileptic disorders by alte ring excitability,but further,by inducing morphological and synaptic abnormalities that are initiated during neocortex formation and may persist into the adult brain.
基金supported by grants from Natural Science Foundation of Hubei Province,China (No. 2010CDB096)the National Key Technology R&D Program of the 12th National Five-year Development Plan of China (No. 2012BAI05B01)
文摘The effects of ATP-sensitive mitochondrial K + channel(mitoK ATP) on mitochondrial membrane potential(Δψm),cell proliferation and protein kinase C alpha(PKCα) expression in airway smooth muscle cells(ASMCs) were investigated.Thirty-six Sprague-Dawley(SD) rats were immunized with saline(controls) or ovalbumin(OVA) with alum(asthma models).ASMCs were cultured from the lung of control and asthma rats.ASMCs were treated with diazoxide(the potent activator of mitoK ATP) or 5-hydroxydencanote(5-HD,the inhibitor of mitoK ATP).Rhodamine-123(R-123) was used to detect Δψm.The expression of PKCα protein was examined by using Western blotting,while PKCα mRNA expression was detected by using real-time PCR.The proliferation of ASMCs was measured by MTT assay and cell cycle analysis.In diazoxide-treated normal ASMCs,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and percentage of cells in S phase were markedly increased as compared with untreated controls.The ratio of G 0 /G 1 cells was decreased(P<0.05) in diazoxide-treated ASMCs from normal rats.However,there were no significant differences between the ASMCs from healthy rats treated with 5-HD and the normal control group.In untreated and diazoxide-treated ASMCs of asthmatic rats,the R-123 fluorescence intensity,protein and mRNA levels of PKCα,MTT A values and the percentage of cells in S phase were increased in comparison to the normal control group.Furthermore,in comparison to ASMCs from asthmatic rats,these values were considerably increased in asthmatic group treated with diazoxide(P<0.05).After exposure to 5-HD for 24 h,these values were decreased as compared with asthma control group(P<0.05).In ASMCs of asthma,the signal transduction pathway of PKCα may be involved in cell proliferation,which is induced by the opening of mitoK ATP and the depolarization of Δψm.
基金supported in part by a Grant from AMED(17ek0109120h0003)a Grant-in-Aid for Scientific Research from the Ministry of Education,Culture,Sports,Science and Technology(17K08324 and 15H04892)
文摘Astrocytic Kir4.1 channels and spatial potassium buffering:Astrocytes play a crucial role in maintaining the structural and functional integrity of the brain,which includes formation of the blood-brain barrier,maintenance of water and ion homeostasis,metabolism of neurotransmitters and secretion of various neuroactive molecules.
文摘The effects of levobunolol hydrochlorid (Bun) on the type L calciumchannel currents (Ica) and delayed rectifier potassium channel currents (Ik) in isolated ventricular myocytes of guinea pig were studied by using patch clamp wholecell recording techniques. The results were showed that: 1) Bun caused a dosedependent decrease in Ica and a dose-dependent increase in Ik of the ventricular myocytes.The threshold concentrations of Bun for Ica and Ik were 10-8 mol/L and10-7 mol/L respectively. The maximum effective concentration of Bun for both Ica and Ik was 3 × 10-5 mol/L, and half-maximal concentration was 3 × 10-6 mol/L;2 ) Ik was blocked by 2× 10-6mol/L tetraethylammonium (TEA). A concentration of 3 × 10-6 mol/L Bun showed a decreasing effect on the Ica as revealed by the current-voltage relationship curve, i. e., Bun caused an elevation of the curve; 3)When Ica was blocked by 2 × 10-6 mol/L Isoptin (Verapamil), at a concentrationof 3 × 106- mol/L Bun showed an increasing effect on Ik and the effect could be blocked by TEA. The above-mentioned results indicated that Bun had an inhibito-ry effect on Ica and a fascilitatory effect on Ik The results suggested that themolecular mechanisms of antihypertensive, heart rate slowing and β-receptorblocking effects of Bun might be due to decrease of Ica and increase of Ik.
基金Supported by the Program of the Network-type Joint Usage/Research Center for Radiation Disaster Medical Science of Hiroshima University,Nagasaki University.
文摘BACKGROUND ATP sensitive K+(K_(ATP))channels are ubiquitously distributed in various of cells and tissues,including the liver.They play a role in the pathogenesis of myocardial and liver ischemia.AIM To evaluate the radiation-induced changes in the expression of K_(ATP)channel subunits in the mouse liver to understand the potential role of K_(ATP)channels in radiation injury.METHODS Adult C57BL/6 mice were randomly exposed toγ-rays at 0 Gy(control,n=2),0.2 Gy(n=6),1 Gy(n=6),or 5 Gy(n=6).The livers were removed 3 and 24 h after radiation exposure.Hematoxylin and eosin staining was used for morphological observation;immunohistochemical staining was applied to determine the expression of K_(ATP)channel subunits in the liver tissue.RESULTS Compared with the control group,the livers exposed to 0.2 Gyγ-ray showed an initial increase in the expression of Kir6.1 at 3 h,followed by recovery at 24 h after exposure.Exposure to a high dose of 5.0 Gy resulted in decreased expression of Kir6.1 and increased expression of SUR2B at 24 h.However,the expression of Kir6.2,SUR1,or SUR2A had no remarkable changes at 3 and 24 h after exposure to any of these doses.CONCLUSION The expression levels of Kir6.1 and SUR2B in mouse liver changed differently in response to different radiation doses,suggesting a potential role for them in radiation-induced liver injury.
文摘There is accumulating evidence that the subfamily of large-conductance potassium (“big”, “BK”) channels are involved in diverse, and perhaps coordinated, protective or counteractive responses to local or generalized ischemia and hypoxia. Although widely distributed, the physiological differences among BK channels which results from posttranslational modification (alternative splicing) and co-assembly with auxiliary modulatory subunits (<em>β</em><sub>1-4</sub> and <em>γ</em><sub>1-4</sub>), bestows localized differences in subunit composition, distribution, 2<sup>nd</sup>-messenger coupling, and pharmacologic properties. Due to the ubiquitous nature of BK channels and the multiplicity of subtypes, they have many potential therapeutic applications in the maintenance of oxygen homeostasis, cerebro- and cardio-protection, and stimulation of respiration in response to drug-induced respiratory depression. BK channels may also offer other potentially broad and underrecognized promising targets for novel pharmaceutical development.
基金supported by the Project Sponsored by Yantai Science and Technology Bureau,China,No.2010232
文摘In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease in PC12 cell viability induced by amyloid-β peptide (25-35). Diazoxide protected PC12 cells against amyloid-β peptide (25-35)-induced increases in mitochondrial membrane potential and intracellular reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nw-nitro-L-arginine, also protected PC12 cells from amyloid-β peptide (25-35)-induced increases in both mitochondrial membrane potential and intracellular reactive oxygen species levels. However, the H202-degrading enzyme catalase could not reverse the amyloid-β peptide (25-35)-induced increase in intracellular reactive oxygen species. A 24-hour exposure to amyloid-13 peptide (25-35) did not result in apoptosis or necrosis, suggesting that the increases in both mitochondrial membrane potential and reactive oxygen species levels preceded cell death. The data suggest that amyloid-β peptide (25-35) cytotoxicity is associated with adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β peptide (25-35).
文摘Objective: To investigate the role of large Ca^2+-activated, delayed-rectifier and ATP-sensitive potassium channel in regulating the relaxation induced by nitric oxide (NO) in normal and passively sensitized human airway smooth muscle (HASM) with serum from asthmatic patients. Methods: The effects of NO or/and potassium channel blockers on the tensions of normal and passively sensitized HASM were measured by using nitric oxide donor and potassium blockers, with the isometric tension recording technique. Results: Showed that(1)In the control group and passively sensitized group, Kv blocker(4-AP) cause concentration-dependent augmentation in the contraction induced by histamine ( 1 ×10^-4 mol/L ), (P 〈 0.05), but Glib ( 1 × 10^-2 mol/L ) and TEA (1×10^-4 mol/L) have no significant effects on the contraction induced by histamine (1×10^-4 mol/L). The maximum tension induced by histamine in passively sensitized group is higher than that in the control group (P 〈 0.05). (2) NO-donor Sodium Nitroprusside (SNP) bring about significant relaxation in normal and passively sensitized HASM rings (P 〈 0.05). Relaxations of passively sensitized airway rings [ (29.4 ± 3.3)% ] were significant less than those of normal HASM rings [ (44.1 ± 10.2)% ], (P 〈 0.05).(3) Glib(1×10^-2 mol/L)have no significant effect on the relaxations induced by SNP(1×10^-4 mol/L). 4-AP(1×10^-2 mol/L) inhibited relaxation induced by SNP (1×10^-4 mol/L), (P 〈 0.01). TEA (1×10^-3 tool/L) inhibited relaxation induced by SNP (1×10^-4 mol/L) (P 〈 0.05), and the inhibiting effect in passively sensitized HASM rings were significant less than in normal HASM, (P 〈 0.05). Conclusion: It was concluded that SNP(NO-donor) relaxed the contraction of HASM partly via BKca channel opening. In passively sensitized HASM in vitro, the relaxation of SNP decreased compared with control group, which might be associated with the down-regulating activity of BKca in passively sensitized HASM.
基金Supported by the Program of the network-type joint Usage/Research Center for Radiation Disaster Medical Science of Hiroshima University,Nagasaki University,and Fukushima Medical University
文摘BACKGROUND ATP-sensitive K^+(KATP)channels were originally found in cardiac myocytes by Noma in 1983.KATP channels were formed by potassium ion-passing poreforming subunits(Kir6.1,Kir6.2)and regulatory subunits SUR1,SU2A and SUR2B.A number of cells and tissues have been revealed to contain these channels including hepatocytes,but detailed localization of these subunits in different types of liver cells was still uncertain.AIM To investigate the expression of KATP channel subunits in rat liver and their localization in different cells of the liver.METHODS Rabbit anti-rat SUR1 peptide antibody was raised and purified by antigen immunoaffinity column chromatography.Four of Sprague-Dawley rats were used for liver protein extraction for immunoblot analysis,seven of them were used for immunohistochemistry both for the ABC method and immunofluorescence staining.Four of Wistar rats were used for the isolation of hepatic stellate cells(HSCs)and Kupffer cells for both primary culture and immunocytochemistry.RESULTS Immunoblot analysis showed that the five kinds of KATP channel subunits,i.e.Kir6.1,Kir6.2,SUR1,SUR2A,and SUR2B,were detected in liver.Immunohistochemical staining showed that Kir6.1 and Kir6.2 were weakly to moderately expressed in parenchymal cells and sinusoidal lining cells,while SUR1,SUR2A,and SUR2B were mainly localized to sinusoidal lining cells,such as HSCs,Kupffer cells,and sinusoidal endothelial cells.Immunoreactivity for SUR2A and SUR2B was expressed in the hepatocyte membrane.Double immunofluorescence staining further showed that the pore-forming subunits Kir6.1 and/or Kir6.2 colocalized with GFAP in rat liver sections and primary cultured HSCs.These KATP channel subunits also colocalized with CD68 in liver sections and primary cultured Kupffer cells.The SUR subunits colocalized with GFAP in liver sections and colocalized with CD68 both in liver sections and primary cultured Kupffer cells.In addition,five KATP channel subunits colocalized with SE-1 in sinusoidal endothelial cells.CONCLUSION Observations from the present study indicated that KATP channel subunits expressed in rat liver and the diversity of KATP channel subunit composition might form different types of KATP channels.This is applicable to hepatocytes,HSCs,various types of Kupffer cells and sinusoidal endothelial cells.
文摘Objectives Ischemia induced arrhythmia(ventricular tachycardia/ventricular fibrillation) is one of the major causes of death.Potassium channels change are likely to be responsible for the ischemia-related arrhythmias.Cardiac potassium current is the major outward current involved in cardiac repolarization.The properties of potassium channels have been intensively studied.Here,we investigated the association between ischemia induced arrhythmia and potassium channels genetic variations.Methods 23 patients with ventricular tachycardia/ventricular fibrillation induced by ischemia were selected as objects.5ML peripheral blood were taken from each person,from which DNA was extracted us- ing a standard enzymatic phenol-chloroform method.Candidate genes(HERG、KCNJ2、KCNQ1、Mink、Mirp1、Kir2.1、KV4.3、Kir3.1、KV1.5、Kir6.1、Kir6.2、Kir2.1) Were screened for potassium channels gene mutations with direct sequencing methods.Results Here 4 potassium channels gene mutations have been discovered.In the gene coding for the ATP-sensitive K^+ channels subunit Kir6.2,there is a change from valine to isoleucine at the position of 326(V326I).At the position 448,arginine substitutes proline(P448R) in the KC-NQ1 gene.In the gene KCNJ2 two mutations have been found(P156L,Q193H).Conclusions This study implicated that there is a high relationship between ischemia induced arrhythmia and the mutation of potassium channels.In order to identify the precisely relationship there is need functional analysis.
文摘Objective: To investigate changes of Ca2+ activated potassium channels (KCa) in autogenous vein grafts. Methods: Contraction of venous ring was measured by means of perfusion in vitro. The intimal rabbits proliferation of vascular and proliferation of cultured smooth muscle cells(vascular smooth muscle cells, VSMCs)were observed by the means of computerised image analysis and MTT method respectively. Furthermore, whole cell mode of patch clamp was used to record KCa of VSMCs isolated from autogenous vein grafts. Results: One week after transplantation there were no significant differences of contraction and intimal relative thickness between autogenous vein grafts and control. Contraction and intimal relative thickness of autogenous vein graft were significantly increased 2 weeks after transplantation (P<0.05, n=8 vs control), and they was more enhanced 4 weeks after vein transplantation (P<0.01, n=8 vs control).TEA(blocker of Ca2+ activated potassium channels)increased MTT A490 nm value of VSMCs from femoral vein in a dose dependent manner(P<0.05, n=8). KCa current density was significantly attenuated in VSMCs from autogenous vein grafts (1-4) week after transplantation(P<0.05, n=5).Conclusion: KCa is inhibited in autogenous vein graft, which account for vasospasm and intimal proliferation.
文摘Uging diet control method to feed the weaning male Wistar rats with selenium and iodine deficiency Keshan endemic area food for 8 weeks to set up animal model. Singal channel recortling in cell attached model was used to measure cardiac cell membrane potassium channel conductances. which coincide with the cardiac cell membrane potassium channel conductances in normal Wistar rats.The potassium channel conductance on selenlum and lodine cleficiency rat cardiac cell membrane is showing current-voltage increasing lineally in the range of clamping volatge 0±30 mV with channel conductance of 43.4 pS. The channel current does not increase depending on the clamping voltage that is showing the rectifying characteristic and the channel current amplitude can be augmented by added KIOa 5 mmol/L in bath solution. A kind of inward rectiyfing potassium channel activity was recorded, but this channel activity disappeared affer lasting 6~ 10 minutes only. Then an inward rectifying potassium channel with the conductance of 11. 2 PS was activated by KIOa 5 mmol/L, introduced to bath solution. Both conductances are less than that of normal Wistar rats.