Objective: To study the effect of simulated ischemia-reperfusion (I/R) on If of sinoatrial node (SAN) cells and the intervention of KATP channel opener Pinacidil. Methods: The SAN cells of the neonatal rats were detac...Objective: To study the effect of simulated ischemia-reperfusion (I/R) on If of sinoatrial node (SAN) cells and the intervention of KATP channel opener Pinacidil. Methods: The SAN cells of the neonatal rats were detached and purified 2 d before the experiment. The experimental animals were randomly divided into the control group, group of simulated I/R, group intervened with KATP channel opener Pinacidil (P+ I/R) and group intervened with KATP channel blocking agent 5-HD (5-HD + P + I/R & 5-HD + I/R). The If density of each group was measured by technique of routine whole cell patch clamp and multiple-catheter perfusion system and the If activated curve in each group was drawn. Results: ①Under different directive potentials, the If density of the SAN cells in I/R group increased significantly, compared with that in the control group ( P < 0.01); that in P + I/R group decreased significantly, compared with that in I/R group ( P < 0.01); the If density values in 5-HD + P + I/R group and 5-HD + I/R group increased significantly, compared with that in P + I/R group, but showed no significant difference with that in I/R group. ②Compared with that in the control group, the If activated curve of the SAN cells moved rightwards under ultimate activating potential, half of which was from - 108.0 ± 12.4 to - 89.5 ± 7.2 mV ( P <0.01); compared with that in I/R group, If activated curve of the SAN cells moved leftwards under ultimate activating potential, half of which was the range from -99.5± 10.8 mV (P<0.05); KATP channel blocking agent 5-HD could block the effect of Pinacdil on If activated curve. Conclusion: KATP channel opener Pinacidil can antagonize the effect of simulated I/R on the If of SAN cells, which may be beneficial to the maintenance of the relative stability of ion steady state and electrophysiological activities under condition of simulated I/R.展开更多
In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） ...In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） since the mutation can influence sodium channel functions. However it is still unclear if the E1784K mutation-induced sodium ionic channel alterations account for the overlap at tissue level. Thsu, a detailed computational model is developed to underpin the functional impacts of the E1784K mutation on the action potential （AP）, the effective refractory period （ERP） and the abnormal ECG. Simulation results stlggest＇that the E1784K mutation-induced sodium channel alterations are insufficient to produce the phenotypic overlap between LQT3 and BrS, and the overlap may arise from the complicated effects of the E1784K mutation-induced changes in sodium channel currents with an increase of the transient outward current ITo or a decrease of the L-type calcium current ICaL .展开更多
A number of studies show that environmental stress conditions increase abscisic acid (ABA) and hydrogen peroxide (H2O2) levels in plant cells. Despite this central role of ABA in altering stomatal aperture by regulati...A number of studies show that environmental stress conditions increase abscisic acid (ABA) and hydrogen peroxide (H2O2) levels in plant cells. Despite this central role of ABA in altering stomatal aperture by regulating guard cell ion transport, little is known concerning the relationship between ABA and H2O2 in signal transduction leading to stomatal movement. Epidermal strip bioassay illustrated that ABA- inhibited stomatal opening and ABA-induced stomatal closure were abolished partly by externally added catalase (CAT) or diphenylene iodonium (DPl), which are a H2O2 scavenger and a NADPH oxidase inhibitor respectively. In contrast, internally added CAT or DPI nearly completely or partly reversed ABA-induced closure in half-stoma. Consistent with these results, whole-cell patch-clamp analysis showed that intracellular application of CAT or DPI partly abolished ABA-inhibited inward K+ current across the plasma membrane of guard cells. H2O2 mimicked ABA to inhibit inward K+ current, an effect which was reversed by the addition of ascorbic acid (Vc) in patch clamping micropipettes. These results suggested that H2O2 mediated ABA-induced stomatal movement by targeting inward K+ channels at plasma membrane.展开更多
The roles of intermediate conductance Ca2＋-activated K＋ channel （IKCal） in the pathogene- sis of hepatocellular carcinoma （HCC） were investigated. Immunohistochemistry and Western blotting were used to detect th...The roles of intermediate conductance Ca2＋-activated K＋ channel （IKCal） in the pathogene- sis of hepatocellular carcinoma （HCC） were investigated. Immunohistochemistry and Western blotting were used to detect the expression of IKCal protein in 50 HCC and 20 para-carcinoma tissue samples. Real-time PCR was used to detect the transcription level of IKCal mRNA in 13 HCC and 11 para-carcinoma tissue samples. The MTT assay was used to measure the function of IKCal in human HCC cell line HepG2 in vitro. TRAM-34, a specific blocker of IKCal, was used to intervene with the function of IKCal. As compared with para-carcinoma tissue, an over-expression of IKCal protein was detected in HCC tissue samples （P〈0.05）. The mRNA expression level of IKCal in HCC tissues was 2.17 times higher than that in para-carcinoma tissues. The proliferation of HepG2 cells was suppressed by TRAM-34 （0.5, 1.0, 2.0 and 4.0 pxnol/L） in vitro （P〈0.05）. Our results suggested that IKCal may play a role in the proliferation of human HCC, and IKCal blockers may represent a potential therapeutic strategy for HCC.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
The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardi...The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardial protection against ischemia,and insulin secretion.The aim of this review is to get insight into the novel roles of KATPchannels in Parkinson＇s disease（PD）,with consideration of the specificities KATPchannels in the central nervous system（CNS）, such as the control of neuronal excitability,action potential,mitochondrial function and neurotransmitter release.展开更多
AIM:To assess the effect of nitric oxide (NO) on the large conductance potassium channel (BKCa) in isolated circular (CM) and sling (SM) muscle cells and muscle strips from the cat lower esophageal sphincter (LES) to ...AIM:To assess the effect of nitric oxide (NO) on the large conductance potassium channel (BKCa) in isolated circular (CM) and sling (SM) muscle cells and muscle strips from the cat lower esophageal sphincter (LES) to determine its regulation of resting tone and relaxation.METHODS:Freshly enzymatically-digested and isolated circular smooth muscle cells were prepared from each LES region.To study outward K + currents,the perforated patch clamp technique was employed.To assess LES resting tone and relaxation,muscle strips were mounted in perfused organ baths.RESULTS:(1) Electrophysiological recordings from isolated cells:(a) CM was more depolarized than SM (-39.7 ± 0.8mV vs-48.1 ± 1.6 mV,P < 0.001),and maximal outward current was similar (27.1 ± 1.5 pA/pF vs 25.7 ± 2.0 pA/pF,P > 0.05);(b) The NO donor sodium nitroprusside (SNP) increased outward currents only in CM (25.9 ± 1.9 to 46.7 ± 4.2 pA/pF,P < 0.001) but not SM (23.2 ± 3.1 to 27.0 ± 3.4 pA/pF,P > 0.05);(c) SNP added in the presence of the BK Ca antagonist iberiotoxin (IbTX) produced no increase in the outward current in CM (17.0 ± 2.8 vs 13.7 ± 2.2,P > 0.05);and (d) L-NNA caused a small insignificant inhibition of outward K + currents in both muscles;and (2) Muscle strip studies:(a) Blockade of the nerves with tetrodotoxin (TTX),or BK Ca with IbTX had no significant effect on resting tone of either muscle;and (b) SNP reduced tone in both muscles,and was unaffected by the presence of TTX or IbTX.CONCLUSION:Exogenous NO activates BK Ca only in CM of the cat.However,as opposed to other species,exogenous NO-induced relaxation is predominantly by a non-BK Ca mechanism,and endogenous NO has minimal effect on resting tone.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
Objective： To investigate the expression of hergl gene in tumor tissues from gastric carcinomas and gastric carcinoma cell lines, and study the relationship between HERG K＋ channel expressions and tumor cell prolife...Objective： To investigate the expression of hergl gene in tumor tissues from gastric carcinomas and gastric carcinoma cell lines, and study the relationship between HERG K＋ channel expressions and tumor cell proliferation and apoptosis. Methods： RT-PCR and PCR assays were used to detect the expression of hergl gene in 64 gastric carcinomas and the gastric cancer cell line SGC-7901. Blocking the HERG K＋ channels was used to evaluate their effects on tumor cell proliferation and apoptosis. Results：The statistically significant expression of hergl gene was detected in all the gastric cancers and SGC-7901 cells, but not in normal tissues. The HERG K＋ channel blocker, E-4031, increased the cell population in G0/G1（P 〈 0.05） and the number of apoptotic tumor cells（P 〈 0.05）. Conclusion： HERG K＋ channels were expressed in all gastric carcinomas tested and these channels appear to modulate tumor cell proliferation and apoptosis.展开更多
基金Supported by National Natural Science Foundation of China (No.30070314)
文摘Objective: To study the effect of simulated ischemia-reperfusion (I/R) on If of sinoatrial node (SAN) cells and the intervention of KATP channel opener Pinacidil. Methods: The SAN cells of the neonatal rats were detached and purified 2 d before the experiment. The experimental animals were randomly divided into the control group, group of simulated I/R, group intervened with KATP channel opener Pinacidil (P+ I/R) and group intervened with KATP channel blocking agent 5-HD (5-HD + P + I/R & 5-HD + I/R). The If density of each group was measured by technique of routine whole cell patch clamp and multiple-catheter perfusion system and the If activated curve in each group was drawn. Results: ①Under different directive potentials, the If density of the SAN cells in I/R group increased significantly, compared with that in the control group ( P < 0.01); that in P + I/R group decreased significantly, compared with that in I/R group ( P < 0.01); the If density values in 5-HD + P + I/R group and 5-HD + I/R group increased significantly, compared with that in P + I/R group, but showed no significant difference with that in I/R group. ②Compared with that in the control group, the If activated curve of the SAN cells moved rightwards under ultimate activating potential, half of which was from - 108.0 ± 12.4 to - 89.5 ± 7.2 mV ( P <0.01); compared with that in I/R group, If activated curve of the SAN cells moved leftwards under ultimate activating potential, half of which was the range from -99.5± 10.8 mV (P<0.05); KATP channel blocking agent 5-HD could block the effect of Pinacdil on If activated curve. Conclusion: KATP channel opener Pinacidil can antagonize the effect of simulated I/R on the If of SAN cells, which may be beneficial to the maintenance of the relative stability of ion steady state and electrophysiological activities under condition of simulated I/R.
基金Supported by the National Natural Science Foundation of China(61001167,61172149)~~
文摘In the clinical reports, the E1784K mutation in SCN5A is recognized as a phenotypic overlap between the long QT syndrome （LQT3） and the Brugada syndrome （BrS） in the characteristics of electrocardiograms （ECGs） since the mutation can influence sodium channel functions. However it is still unclear if the E1784K mutation-induced sodium ionic channel alterations account for the overlap at tissue level. Thsu, a detailed computational model is developed to underpin the functional impacts of the E1784K mutation on the action potential （AP）, the effective refractory period （ERP） and the abnormal ECG. Simulation results stlggest＇that the E1784K mutation-induced sodium channel alterations are insufficient to produce the phenotypic overlap between LQT3 and BrS, and the overlap may arise from the complicated effects of the E1784K mutation-induced changes in sodium channel currents with an increase of the transient outward current ITo or a decrease of the L-type calcium current ICaL .
基金National Natura1 Science Foundation of China (No. 39870372),StateKey Basic Research and Development Project (No.G1999011700)
文摘A number of studies show that environmental stress conditions increase abscisic acid (ABA) and hydrogen peroxide (H2O2) levels in plant cells. Despite this central role of ABA in altering stomatal aperture by regulating guard cell ion transport, little is known concerning the relationship between ABA and H2O2 in signal transduction leading to stomatal movement. Epidermal strip bioassay illustrated that ABA- inhibited stomatal opening and ABA-induced stomatal closure were abolished partly by externally added catalase (CAT) or diphenylene iodonium (DPl), which are a H2O2 scavenger and a NADPH oxidase inhibitor respectively. In contrast, internally added CAT or DPI nearly completely or partly reversed ABA-induced closure in half-stoma. Consistent with these results, whole-cell patch-clamp analysis showed that intracellular application of CAT or DPI partly abolished ABA-inhibited inward K+ current across the plasma membrane of guard cells. H2O2 mimicked ABA to inhibit inward K+ current, an effect which was reversed by the addition of ascorbic acid (Vc) in patch clamping micropipettes. These results suggested that H2O2 mediated ABA-induced stomatal movement by targeting inward K+ channels at plasma membrane.
基金supported by grants from the National Natural Science Foundation of China (No. 81072001)the Natural Science Foundation of Hubei Province, China (No.2011CDB556)
文摘The roles of intermediate conductance Ca2＋-activated K＋ channel （IKCal） in the pathogene- sis of hepatocellular carcinoma （HCC） were investigated. Immunohistochemistry and Western blotting were used to detect the expression of IKCal protein in 50 HCC and 20 para-carcinoma tissue samples. Real-time PCR was used to detect the transcription level of IKCal mRNA in 13 HCC and 11 para-carcinoma tissue samples. The MTT assay was used to measure the function of IKCal in human HCC cell line HepG2 in vitro. TRAM-34, a specific blocker of IKCal, was used to intervene with the function of IKCal. As compared with para-carcinoma tissue, an over-expression of IKCal protein was detected in HCC tissue samples （P〈0.05）. The mRNA expression level of IKCal in HCC tissues was 2.17 times higher than that in para-carcinoma tissues. The proliferation of HepG2 cells was suppressed by TRAM-34 （0.5, 1.0, 2.0 and 4.0 pxnol/L） in vitro （P〈0.05）. Our results suggested that IKCal may play a role in the proliferation of human HCC, and IKCal blockers may represent a potential therapeutic strategy for HCC.
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the National Natural Science Foundation of China（No.30700251）；the National Basic Research Development Program of China（No.2006CB500706）；the Young Excellent Scholar（2007-2008）Program of Shanghai Jiaotong University School of Medicine.
文摘The ATP-sensitive potassium（KATP）channels which extensively distribute in diverse tissues（e.g.vascular smooth muscle,cardiac cells,and pancreas）are well-established for characteristics like vasodilatation,myocardial protection against ischemia,and insulin secretion.The aim of this review is to get insight into the novel roles of KATPchannels in Parkinson＇s disease（PD）,with consideration of the specificities KATPchannels in the central nervous system（CNS）, such as the control of neuronal excitability,action potential,mitochondrial function and neurotransmitter release.
基金Supported by A Postgraduate Fellowship Award to L'Heureux MC from the Department of Medicine,University of Torontoa doctoral research studentship and an Operating Grant from the Canadian Institutes of Health Research(Gaisano HY and Diamant NE)
文摘AIM:To assess the effect of nitric oxide (NO) on the large conductance potassium channel (BKCa) in isolated circular (CM) and sling (SM) muscle cells and muscle strips from the cat lower esophageal sphincter (LES) to determine its regulation of resting tone and relaxation.METHODS:Freshly enzymatically-digested and isolated circular smooth muscle cells were prepared from each LES region.To study outward K + currents,the perforated patch clamp technique was employed.To assess LES resting tone and relaxation,muscle strips were mounted in perfused organ baths.RESULTS:(1) Electrophysiological recordings from isolated cells:(a) CM was more depolarized than SM (-39.7 ± 0.8mV vs-48.1 ± 1.6 mV,P < 0.001),and maximal outward current was similar (27.1 ± 1.5 pA/pF vs 25.7 ± 2.0 pA/pF,P > 0.05);(b) The NO donor sodium nitroprusside (SNP) increased outward currents only in CM (25.9 ± 1.9 to 46.7 ± 4.2 pA/pF,P < 0.001) but not SM (23.2 ± 3.1 to 27.0 ± 3.4 pA/pF,P > 0.05);(c) SNP added in the presence of the BK Ca antagonist iberiotoxin (IbTX) produced no increase in the outward current in CM (17.0 ± 2.8 vs 13.7 ± 2.2,P > 0.05);and (d) L-NNA caused a small insignificant inhibition of outward K + currents in both muscles;and (2) Muscle strip studies:(a) Blockade of the nerves with tetrodotoxin (TTX),or BK Ca with IbTX had no significant effect on resting tone of either muscle;and (b) SNP reduced tone in both muscles,and was unaffected by the presence of TTX or IbTX.CONCLUSION:Exogenous NO activates BK Ca only in CM of the cat.However,as opposed to other species,exogenous NO-induced relaxation is predominantly by a non-BK Ca mechanism,and endogenous NO has minimal effect on resting tone.
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 a grant from the Natural Science Foundation of China(30772128)
文摘Objective： To investigate the expression of hergl gene in tumor tissues from gastric carcinomas and gastric carcinoma cell lines, and study the relationship between HERG K＋ channel expressions and tumor cell proliferation and apoptosis. Methods： RT-PCR and PCR assays were used to detect the expression of hergl gene in 64 gastric carcinomas and the gastric cancer cell line SGC-7901. Blocking the HERG K＋ channels was used to evaluate their effects on tumor cell proliferation and apoptosis. Results：The statistically significant expression of hergl gene was detected in all the gastric cancers and SGC-7901 cells, but not in normal tissues. The HERG K＋ channel blocker, E-4031, increased the cell population in G0/G1（P 〈 0.05） and the number of apoptotic tumor cells（P 〈 0.05）. Conclusion： HERG K＋ channels were expressed in all gastric carcinomas tested and these channels appear to modulate tumor cell proliferation and apoptosis.
