Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippoc...Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current (IK(DR)) and transient outward potassium current (I_K(A)) in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student's paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited IK(DR) by 49.2% at +40 mV when depolarized from -110 mV (P 〈0.01, n=8), while did not affect IK(A) (/1=8, P 〉0.05). The IC50value of etomidate for blocking IK(DR)was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V1/2 of activation curve was shifted from (17.3±1.5) mV to (10.7±9.9) mV (n=8, P 〈0.05), the V1/2 of inactivation curve was shifted from (-18.3±2.2) mV to (-45.3±9.4) mV (n=8, P 〈0.05). Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of IK(DR))to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited IK(DR) but not IK(A) in rat hippocampal pyramidal neurons. IK(DR) was inhibited by etomidate in a concentration-dependent manner, while IK(A) remained unaffected.展开更多
OBJECTIVE Stroke has become the top ten leading cause of death in China.Isch⁃emic stroke accounts for 85%of stroke cases,and insufficiency of cerebral blood supply caused by atherosclerosis is one of the important cau...OBJECTIVE Stroke has become the top ten leading cause of death in China.Isch⁃emic stroke accounts for 85%of stroke cases,and insufficiency of cerebral blood supply caused by atherosclerosis is one of the important causes of ischemic stroke.Therefore,it is of posi⁃tive significance to study the molecular mecha⁃nism of stroke injury caused by hypoperfusion in the search for drug targets.Voltage-dependent potassium channels are a family of potassium channels widely expressed in the central ner⁃vous system.However,their roles in neurogene⁃sis after stroke insults have not been clearly illus⁃trated.The purpose of this experiment is to explore the expression changes of different sub⁃families of voltage-dependent potassium chan⁃nels after the occurrence of ischemic stroke and their influence on neuroregeneration,to study the molecular mechanism of stroke injury caused by hypoperfusion,and to find potential targets for drug therapy of ischemic stroke.METHODS C57BL/6 mice aged 7-8 weeks and C17.2 cells were used in vivo and in vitro in the experiment.The mice in the experimental group were suf⁃fered from bilateral common carotid artery occlu⁃sion(BCCO)for 1 h and reperfusion for 7 d.In the control group,bilateral carotid artery was dis⁃sected without occlusion.Behavioral assay of suspension test were performed to assess the motor deficits of the mice.In this assay,the time of the first drop(latency),the number of drops within one minute(frequency),and the final scores were recorded as the results of athletic ability.A lower score indicated more severe motor damage of the mice.TTC staining was used to observe the cerebral infarction areas caused by ligation of bilateral common carotid arteries.After seven days,mice were sacrificed and brain tissue protein samples were collected for real-time quantitative PCR(RT-PCR)and Western blotting test to detect the changes of potassium channel subfamily expression levels in different brain regions.Neuronal injuries in all brain regions were detected using Nissl staining methods 7 d following model establishment.To detect the effects and the underlying mechanism of the related potassium channel on neurogene⁃sis,recombinant plasmids of the potassium chan⁃nels were transfected in cultured C17.2 neural stem cells.Afterwards,oxygen glucose depriva⁃tion experiments were performed.RESULTS Behavioral tests showed that BCCO can cause impaired motor performance.TTC staining showed that cerebral infarction existed in the stri⁃atum region,and the motor function decline caused by the injury in this region was consistent with the behavioral experiment results which veri⁃fied the effectiveness of our surgical operation.Nissl staining revealed a large amount of neuronal cell necrosis in the cortex and striatum regions,and dense neuronal cells in the lateral ventricular limbic region,suggesting that neurogenesis may have occurred in this region.The results of real-time quantitative RT-PCR showed that among the detected potassium channels distributed in the measured nervous system,the expression of voltage-dependent potassium channel Kv4.2 decreased significantly in all brain regions after stroke,suggesting that it may be involved in the pathological process of stroke.Immunohisto⁃chemical staining showed that there was neuro⁃genesis in the subgranular zone(SGZ)and sub⁃ventricular zone(SVZ)of the mice,and Kv4.2 expression was significantly changed in the regions,suggesting that it may be involved in the regulation of neuro regeneration after stroke.The transfected Kv4.2 plasmid enhanced the dif⁃ferentiation of the C17.2 neural stem cells to neu⁃rons and astrocytes under normoxia and the oxy⁃gen-glucose deprivation,suggesting that Kv4.2 may induce the differentiation of neural stem cells after stroke.Kv4.2 could induce the neural stem cells to differentiate into neurons in vitro and in vivo,and Western blotting assay showed that Kv4.2 could up-regulate the expression level of ERK1/2,p-ERK1/2,p-STAT3,NGF,p-TtkA,and BDNF.Moreover,the calcium ions and CAMKⅡwas also increased by Kv4.2 in vitro.CONCLUSION BCCO insults can induce the expressions of the potassium channels in the brains,among which the expression of Kv4.2 is down-regulated in the cerebral cortex,hippocam⁃pus and striatum.In vitro experiments confirmed that Kv4.2 can induce the differentiation of C17.2 neural stem cells into neurons and astrocytes under the condition of normoxia and oxygen-glucose deprivation.We concluded that Kv4.2 possibly promoted neurogenesis through ERK1/2/STAT3,NGF/TrkA,and Ca2+/CAMKⅡsignal pathways after stroke.Regulating the physiologi⁃cal functions of Kv4.2 channel might contribute to the rehabilitation of neuronal damage after stroke.展开更多
This study was to investigate the main traits of potassium-enriched, flue-cured tobacco genotypes related to potassium absorption, accumulation, and in-ward potassium currents of the root cortex. Hydroponic methods, K...This study was to investigate the main traits of potassium-enriched, flue-cured tobacco genotypes related to potassium absorption, accumulation, and in-ward potassium currents of the root cortex. Hydroponic methods, K^+-depletion methods, and patch-clamp, whole-cell recordings were conducted to study the accumulation of dry matter and potassium in different organs, and to measure potassium absorption and dynamic and in-ward potassium currents in potassium-enriched, fluecured tobacco genotypes. The average dry weights of leaves and whole plant of potassium-enriched, flue-cured tobacco genotype ND202 were 10.20, and 14.85 g, respectively, higher than JYH (8.50 and 13.11 g, respectively) and NC2326 (8.39 and 12.72 g, respectively), when potassium concentration in the solution ranged from 0.1 to 50 mmol L^-1. Potassium accumulation in the leaves of ND202 was 18.6% higher than JYH and 34% higher than NC2326 when potassium concentration in the solution was superior to 0.5 mmol L^-1. The Vmax (the maximum velocity) of ND202 was 118.11 lamol FW g^-1 h^-1, obviously higher than that of JYH (58.87 μmol FW g^-1 h^-1) and NC2326 (64.40 μmol FW g^-1 h^-1). In the in-ward potassium currents, the absolute value of current density (pA/pF) of ND202 was 60, higher than that of JYH (50) and NC2326 (40). Potassium concentration in leaves, Vmax, and in-ward potassium currents, could be used to screen potassium-enriched, flue-cured tobacco genotypes.展开更多
The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of...The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor, and the electrophysiological properties of the voltage-gated potassium ion channels were observed. Immunofluorescence staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin. The differentiated neurons were shown to express neuron-specific enolase. Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S + G2/M phase was high. However, the ratio of cells in the S + G2/M phase decreased obviously as differentiation proceeded. Whole-cell patch-clamp re- cordings revealed apparent changes in potassium ion currents as the neurons differentiated. The potassium ion currents consisted of one transient outward potassium ion current and one delayed rectifier potassium ion current, which were blocked by 4-aminopyridine and tetraethylammonium, respectively. The experimental findings indicate that neural stem cells from newborn rat hippo- campus could be cultured and induced to differentiate into functional neurons under defined condi- tions in vitro. The differentiated neurons expressed two types of outward potassium ion cur'ents similar to those of mature neurons in vivo.展开更多
The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier...The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier K+ outward currents were measured in isolated guinea pig single myocytes using the whole-cell configuration of the patch-clamp technique. Currents were measured in response to 300 ms depolarizing pulses from a holding potential of -40 mV in three experimental protocols [control, isoproterenol (10^(9)mol/L - 10^(-6) mol/L ), and isoproterenol (10^(-9)mol/L - 10^(-6)mol/L ) plus either d, l-Sotalol (10^(-4) mol/L) or d-Sotalol (10^(-4) mol/L)]. IK tail currents were measured upon repolarization to -40 mV. It was found that Ik was significantly amplified in the presence. of isoproterenol (10^(-9) mol/L- 10^(-6) mol/L) plus d-Sotalol. At 10-8 mol/L isoproterenol, Ik was increased by 92. 7%±17. 1 % (P<0. 05) and 54. 3 %±13. 4 % after d-Sotalol addition (P<0. 05). In contrast, d, l-Sotalol completely conteracted the increase of iK by isoproterenol (<10^(-8) mol/L), and compared to control, Ic was decreased by 35. 6 % ±8. 1% at 10^(-8) mol/L isoproterenol plus d, l-Sotalol (P<0. 05). It is concluded that the β-adrenergic blocking property of d, l-Sotalol but not that of dSotalol maintains the delayed rectifier K+ outward current blockade in the presence of isoproterenol in guinea pig myocytes. This might contribute to a superior antiarrhythmic efficacy as compared to d-Sotalol.展开更多
The transmural heterogeneous changes of transient outward potassium currents (Ito) in rabbit hypertrophic cardiaomyocytes and the effects of long-term prophylactic treatment with volsartan were investigated. Rabbits w...The transmural heterogeneous changes of transient outward potassium currents (Ito) in rabbit hypertrophic cardiaomyocytes and the effects of long-term prophylactic treatment with volsartan were investigated. Rabbits were divided into hypertrophy group (left ventricular hypertrophy induced by partial ligation of abdominal aorta), vol-treated group (volsartan was administrated after the ligation), and control group (sham operated). Myocytes were isolated by a two-step enzymatical method. The sub-endocardial (Endo) and sub-epicardium (Epi) tissues were separated from midmyocardium (Mid) with a razor. Whole-cell patch-clamp technique was used to record potassium currents. The results showed that membrane capacitance was larger in hypertrophic cells than those in control and vol-treated cells (P<0.01 vs control cells, n=30). The densities of Ito in hypertrophic cells were reduced by sub-epicardium (Epi) (27.8±2.9) %, midmyocardium (Mid) (41.0±4.7) %, and sub-endocardium (Endo) (20.3±3.4) % compared with those in control cells. The decrease of Ito density was more pronounced in Mid than in Epi and Endo (P<0.01 vs Epi or Endo). There were no significant differences in Ito densities between vol-treated group and control group in three layers separately. In conclusion, volsartan can inhibit the transmural heterogeneous changes of Ito in left ventricular hypertrophic cardiomyocytes in rabbit.展开更多
We used RNA interference (RNAi) to disrupt synthesis of the cortical neuronal y-aminobutyric acid A receptor (GABAAR) al in rats during development, and measured outward K+ currents during neuronal electrical act...We used RNA interference (RNAi) to disrupt synthesis of the cortical neuronal y-aminobutyric acid A receptor (GABAAR) al in rats during development, and measured outward K+ currents during neuronal electrical activity using whole-cell patch-clamp techniques. Three pairs of small interfering RNA (siRNA) for GABAAR al subunit were designed using OligoEngine RNAi software. This siRNA was found to effectively inhibited GABAAR al mRNA expression in cortical neuronal culture in vitro, but did not significantly affect neuronal survival. Outward K^currents were decreased, indicating that GABAAR al subunits in developing neurons participate in neuronal function by regulating outward K+ current.展开更多
To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (I to), delayed rectifier potassium current (I K)...To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (I to), delayed rectifier potassium current (I K) and inward rectifier potassium current (I K1) of left ventricular myocytes in non-infarcted zone of HMI were investigated. Rabbits were randomly assigned into two groups: HMI group, in which animals were subjected to thoracotomy and ligation of the circumflex coronary and sham-operated group, in which rabbits underwent thoracotomy but no conorary ligation. 3 months after the operation, the whole myocyte patch clamp technique was used to record APD, I to, I K, and I K1 of ventricular myocytes in non-infarcted zone.Our results showed that the membrane capacitance was larger in HMI group than in sham-operated group. Action potential duration was significantly lengthened in HMI group and early afterdepolarization (EAD) appeared in HMI group. The densities of I to, I K, tail, and I K1 were reduced significantly in HMI group, from 6.72±0.42 pA/pF, 1.54±0.13 pA/pF and 25.6±2.6 pA/pF in sham-operated group to 4.03±0.33 pA/pF, 1.14±0.11 pA/pF and 17.6 ±2.3 pA/pF, respectively. It is concluded that the reduced densities of I to , I K, tail and I K1 in ventricular myocytes of non-infarcted zone in HMI were responsible for the prolongation of APD and the presentation of EAD which played important roles in the development of malignant arrhythmia in HMI.展开更多
Objective:To study the effect of lycium barbarum polysaccharides (LBP) on high glucose-induced retinal ganglion cell apoptosis, gene expression and delayed rectifier potassium current.Methods: RGC-5 retinal ganglion c...Objective:To study the effect of lycium barbarum polysaccharides (LBP) on high glucose-induced retinal ganglion cell apoptosis, gene expression and delayed rectifier potassium current.Methods: RGC-5 retinal ganglion cell lines were cultured and divided into control group, high glucose group and LBP group that were treated with normal DMEM, high-glucose DMEM as well as high-glucose DMEM containing 500 ng/mL LBP respectively. After treatment, the Annexin V-FITC/PI kits were used to measure the number of apoptotic cells, fluorescence quantitative PCR kits were used to determine the expression of apoptosis genes and antioxidant genes, and patch clamp was used to test delayed rectifier potassium current. Results:12, 24, 36 and 48 h after intervention, the number of apoptotic cells of high glucose group was significantly higher than that of control group, and the number of apoptotic cells of LBP group was significantly lower than that of high glucose group (P<0.05);24 and 48 h after intervention, c-fos, c-jun, caspase-3, caspase-9, Nrf-2, NQO1 and HO-1 mRNA expression as well as potassium current amplitude (IK) and maximum conductance (Gmax) of high glucose group were significantly higher than those of control group while half maximum activation voltage (V1/2) was significantly lower than that of control group (P<0.05);c-fos, c-jun, caspase-3 and caspase-9 mRNA expression as well as IKand Gmaxof LBP group were significantly lower than those of high glucose group, while Nrf-2, NQO1 and HO-1 mRNA expression as well as V1/2 of LBP group were significantly higher than those of high glucose group (P<0.05).Conclusions:LBP can reduce the high glucose-induced retinal ganglion cell apoptosis and inhibit the delayed rectifier potassium current amplitude.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
To investigate the effect of intedeukin-1β (IL-1β) on IA and IK currents in cultured murine trigeminal ganglion (TG) neurons, whole-cell patch clamp technique was used to record the IA and IK currents before and...To investigate the effect of intedeukin-1β (IL-1β) on IA and IK currents in cultured murine trigeminal ganglion (TG) neurons, whole-cell patch clamp technique was used to record the IA and IK currents before and after 20 ng/mL IL-1β perfusion. Our results showed that 20 ng/mL IL-1β inhibited IA currents (18.3±10.7)% (n=6, P〈0.05). IL-1β at 20 ng/mL had no effect on G-V curve of IA but moved the H-infinity curve V0.5 from -36.6±6. 1 mV to-42.4±5.2 mV (n=5, P〈0.01). However, 20 ng/mL IL-1β had effect on neither the amplitude nor the G-V curve of IK. IL-1β was found to selectively inhibit IA current in TG neurons and the effect may contribute to hyperalgesia under various inflammatory conditions.展开更多
A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosa...A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosage of potassium bromide, the temperature and concentration of concomitant substances were investigated in detail. The experimental results indicated that this method was simple, rapid, and sensitive. The linear range was 8.367 × 10(?4) to 2.789 × 10(?2) mol L(?1), the relative standard deviation (R.S.D.) was lower than 0.96%, and the spiked recoveries of aniline in environmental water samples were in the range of 99.4–106.9% under the optimal conditions. The results indicated that the present method could be used as an alternative method for aniline determination in realworld water samples.展开更多
The current difference between male and female rabbit ventricular myocytes was investigated for elucidating the mechanism of longer QT interval and higher incidence of drug-associated torsade de pointes in female rabb...The current difference between male and female rabbit ventricular myocytes was investigated for elucidating the mechanism of longer QT interval and higher incidence of drug-associated torsade de pointes in female rabbits than in male rabbits. Whole cell patch clamp technique was used to record APD, I_to, I_K,tail, I_K1 and I_Ca,L of myocytes from left ventricular apex. There was no difference in the membrane capacitance between male and female rabbit myocytes. APD_90 was longer in female rabbits (560.4±26.5 ms, n=15) than in male ones (489.0±20.7 ms, n=14), P<0.05. In female rabbit myocytes, I_K,tail, I_to, I_K1 and I_Ca,L were 0.71±0.05 pA/pF (n=17), 8.28±1.03 pA/pF (n=18), 24.5±3.6 pA/pF (n=12) and 9.0±2.3 pA/pF (n=15) respectively. In male rabbit myocytes, they were 0.84±0.07 pA/pF (n=18), 8.60±1.20 pA/pF (n=18), 25.9±4.5 pA/pF (n=14) and 9.3±2.6 pA/pF (n=16) respectively. I_K,tail in female rabbits was significantly lower than that of male rabbits (P<0.05), but there was no difference in I_to, I_K1 and I_Ca,L between male rabbits and female rabbits (P>0.05). The lower I_K,tail of female rabbit myocytes may contribute to the longer repolarization and the higher incidence of drug-associated torsade de pointes.展开更多
Many rat taste receptor cells conduct action potentials(APs).APs had a mean threshold of -35 mV(n=95 cells)and a spike height of 52mV above threshold in current clamp(hold= -80mV).Aps could be classified into two sign...Many rat taste receptor cells conduct action potentials(APs).APs had a mean threshold of -35 mV(n=95 cells)and a spike height of 52mV above threshold in current clamp(hold= -80mV).Aps could be classified into two significantly different (P<0.001) groups-fast,with short half-time durations and large outward currents (mean1.3 ms and 2.7nA),and slow,with long duration and small outward currents(mean9.2ms and 0. 29nA).AP upstrokes were conducted by TTX-sensitive sodium currents whereas the downstroke by TEA-blockable outward currents. Voltage dependent analysis of outward current separated transient and sustained components.The transient component was specifically blocked by 4-AP(1mmol/L).A calcium-dependent outward component was also revealed modulating voltage and external calcium concentration.The fast recovery phase of the AP appears related the sustained outward current whereas the after hyperpolarization(AHP) was blocked by 4AP suggesting a significant contribution of the transient component.Forskolin (FSK),which elevates cAMP,reversibly blocked the majority of the sustained current without influencing the transient. FSK greatly exaggerated the AHP without changing the spike height or duration. These data suggest that several components of the outward current contribute specifically to the gustatory AP and that the AP may be modulated by cyclic nucleotides.展开更多
Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field,and the characteristics of transient outward K+ channel were studied using the whole-cell patch-clamp technique.The e...Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field,and the characteristics of transient outward K+ channel were studied using the whole-cell patch-clamp technique.The experiment revealed that the amplitude of transient outward potassium channel current was reduced.The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12,P<0.01) respectively.The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current.Due to the magnetic field exposure,the half-activation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12,P<0.05) ,and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12,P<0.05) .The half-inactivation voltage of the inactivation curves also changed from-56.09±0.89 mV to-57.16±1.10 mV(n=12,P>0.05) and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12,P<0.05) .The results show that the static magnetic field can change the characteristics of transient outward K+ channel,and affect the physiological functions of neurons.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
Engineering design of battery configurations and new battery system development are alternative approaches to achieve high performance batteries. A novel flexible and ultra-light graphite anode is fabricated by simple...Engineering design of battery configurations and new battery system development are alternative approaches to achieve high performance batteries. A novel flexible and ultra-light graphite anode is fabricated by simple friction drawing on filter paper with a commercial 8 B pencil.Compared with the traditional anode using copper foil as current collector, this innovative current-collector-free design presents capacity improvement of over 200% by reducing the inert weight of the electrode. The as-prepared pencil-trace electrode exhibits excellent rate performance in potassium-ion batteries(KIBs), significantly better than in lithium-ion batteries(LIBs), with capacity retention of 66% for the KIB vs. 28% for the LIB from 0.1 to 0.5 A g^(-1). It also shows a high reversible capacity of ~230 mAh g^(-1) at 0.2 A g^(-1), 75% capacity retention over350 cycles at 0.4 A g^(-1)and the highest rate performance(based on the total electrode weight) among graphite electrodes for K+ storage reported so far.展开更多
基金This study was supported by a grant from the National Nature Science Foundation of China (No. 30672030).
文摘Background Previous studies demonstrated general anesthetics affect potassium ion channels, which may be one of the mechanisms of general anesthesia. Because the effect of etomidate on potassium channels in rat hippocampus which is involved in memory function has not been studied, we investigated the effects of etomidate on both delayed rectifier potassium current (IK(DR)) and transient outward potassium current (I_K(A)) in acutely dissociated rat hippocampal pyramidal neurons.Methods Single rat hippocampal pyramidal neurons from male Wistar rats of 7-10 days were acutely dissociated by enzymatic digestion and mechanical dispersion according to the methods of Kay and Wong with slight modification. Voltage-clamp recordings were performed in the whole-cell patch clamp configuration. Currents were recorded with a List EPC-10 amplifier and data were stored in a computer using Pulse 8.5. Student's paired two-tail t test was used for data analysis. Results At the concentration of 100 μmol/L, etomidate significantly inhibited IK(DR) by 49.2% at +40 mV when depolarized from -110 mV (P 〈0.01, n=8), while did not affect IK(A) (/1=8, P 〉0.05). The IC50value of etomidate for blocking IK(DR)was calculated as 5.4 μmol/L, with a Hill slope of 2.45. At the presence of 10 μmol/L etomidate, the V1/2 of activation curve was shifted from (17.3±1.5) mV to (10.7±9.9) mV (n=8, P 〈0.05), the V1/2 of inactivation curve was shifted from (-18.3±2.2) mV to (-45.3±9.4) mV (n=8, P 〈0.05). Etomidate 10 μmol/L shifted both the activation curve and inactivation curve of IK(DR))to negative potential, but mainly affected the inactivation kinetics.Conclusions Etomidate potently inhibited IK(DR) but not IK(A) in rat hippocampal pyramidal neurons. IK(DR) was inhibited by etomidate in a concentration-dependent manner, while IK(A) remained unaffected.
文摘OBJECTIVE Stroke has become the top ten leading cause of death in China.Isch⁃emic stroke accounts for 85%of stroke cases,and insufficiency of cerebral blood supply caused by atherosclerosis is one of the important causes of ischemic stroke.Therefore,it is of posi⁃tive significance to study the molecular mecha⁃nism of stroke injury caused by hypoperfusion in the search for drug targets.Voltage-dependent potassium channels are a family of potassium channels widely expressed in the central ner⁃vous system.However,their roles in neurogene⁃sis after stroke insults have not been clearly illus⁃trated.The purpose of this experiment is to explore the expression changes of different sub⁃families of voltage-dependent potassium chan⁃nels after the occurrence of ischemic stroke and their influence on neuroregeneration,to study the molecular mechanism of stroke injury caused by hypoperfusion,and to find potential targets for drug therapy of ischemic stroke.METHODS C57BL/6 mice aged 7-8 weeks and C17.2 cells were used in vivo and in vitro in the experiment.The mice in the experimental group were suf⁃fered from bilateral common carotid artery occlu⁃sion(BCCO)for 1 h and reperfusion for 7 d.In the control group,bilateral carotid artery was dis⁃sected without occlusion.Behavioral assay of suspension test were performed to assess the motor deficits of the mice.In this assay,the time of the first drop(latency),the number of drops within one minute(frequency),and the final scores were recorded as the results of athletic ability.A lower score indicated more severe motor damage of the mice.TTC staining was used to observe the cerebral infarction areas caused by ligation of bilateral common carotid arteries.After seven days,mice were sacrificed and brain tissue protein samples were collected for real-time quantitative PCR(RT-PCR)and Western blotting test to detect the changes of potassium channel subfamily expression levels in different brain regions.Neuronal injuries in all brain regions were detected using Nissl staining methods 7 d following model establishment.To detect the effects and the underlying mechanism of the related potassium channel on neurogene⁃sis,recombinant plasmids of the potassium chan⁃nels were transfected in cultured C17.2 neural stem cells.Afterwards,oxygen glucose depriva⁃tion experiments were performed.RESULTS Behavioral tests showed that BCCO can cause impaired motor performance.TTC staining showed that cerebral infarction existed in the stri⁃atum region,and the motor function decline caused by the injury in this region was consistent with the behavioral experiment results which veri⁃fied the effectiveness of our surgical operation.Nissl staining revealed a large amount of neuronal cell necrosis in the cortex and striatum regions,and dense neuronal cells in the lateral ventricular limbic region,suggesting that neurogenesis may have occurred in this region.The results of real-time quantitative RT-PCR showed that among the detected potassium channels distributed in the measured nervous system,the expression of voltage-dependent potassium channel Kv4.2 decreased significantly in all brain regions after stroke,suggesting that it may be involved in the pathological process of stroke.Immunohisto⁃chemical staining showed that there was neuro⁃genesis in the subgranular zone(SGZ)and sub⁃ventricular zone(SVZ)of the mice,and Kv4.2 expression was significantly changed in the regions,suggesting that it may be involved in the regulation of neuro regeneration after stroke.The transfected Kv4.2 plasmid enhanced the dif⁃ferentiation of the C17.2 neural stem cells to neu⁃rons and astrocytes under normoxia and the oxy⁃gen-glucose deprivation,suggesting that Kv4.2 may induce the differentiation of neural stem cells after stroke.Kv4.2 could induce the neural stem cells to differentiate into neurons in vitro and in vivo,and Western blotting assay showed that Kv4.2 could up-regulate the expression level of ERK1/2,p-ERK1/2,p-STAT3,NGF,p-TtkA,and BDNF.Moreover,the calcium ions and CAMKⅡwas also increased by Kv4.2 in vitro.CONCLUSION BCCO insults can induce the expressions of the potassium channels in the brains,among which the expression of Kv4.2 is down-regulated in the cerebral cortex,hippocam⁃pus and striatum.In vitro experiments confirmed that Kv4.2 can induce the differentiation of C17.2 neural stem cells into neurons and astrocytes under the condition of normoxia and oxygen-glucose deprivation.We concluded that Kv4.2 possibly promoted neurogenesis through ERK1/2/STAT3,NGF/TrkA,and Ca2+/CAMKⅡsignal pathways after stroke.Regulating the physiologi⁃cal functions of Kv4.2 channel might contribute to the rehabilitation of neuronal damage after stroke.
文摘This study was to investigate the main traits of potassium-enriched, flue-cured tobacco genotypes related to potassium absorption, accumulation, and in-ward potassium currents of the root cortex. Hydroponic methods, K^+-depletion methods, and patch-clamp, whole-cell recordings were conducted to study the accumulation of dry matter and potassium in different organs, and to measure potassium absorption and dynamic and in-ward potassium currents in potassium-enriched, fluecured tobacco genotypes. The average dry weights of leaves and whole plant of potassium-enriched, flue-cured tobacco genotype ND202 were 10.20, and 14.85 g, respectively, higher than JYH (8.50 and 13.11 g, respectively) and NC2326 (8.39 and 12.72 g, respectively), when potassium concentration in the solution ranged from 0.1 to 50 mmol L^-1. Potassium accumulation in the leaves of ND202 was 18.6% higher than JYH and 34% higher than NC2326 when potassium concentration in the solution was superior to 0.5 mmol L^-1. The Vmax (the maximum velocity) of ND202 was 118.11 lamol FW g^-1 h^-1, obviously higher than that of JYH (58.87 μmol FW g^-1 h^-1) and NC2326 (64.40 μmol FW g^-1 h^-1). In the in-ward potassium currents, the absolute value of current density (pA/pF) of ND202 was 60, higher than that of JYH (50) and NC2326 (40). Potassium concentration in leaves, Vmax, and in-ward potassium currents, could be used to screen potassium-enriched, flue-cured tobacco genotypes.
基金supported by the National Natural Science Foundation of China,No.31000514the Scientific Research Project for Talent with High Education of Xinxiang Medical University,No.2007502002
文摘The electrophysiological properties of potassium ion channels are regarded as a basic index for determining the functional differentiation of neural stem cells. In this study, neural stem cells from the hippocampus of newborn rats were induced to differentiate with neurotrophic growth factor, and the electrophysiological properties of the voltage-gated potassium ion channels were observed. Immunofluorescence staining showed that the rapidly proliferating neural stem cells formed spheres in vitro that expressed high levels of nestin. The differentiated neurons were shown to express neuron-specific enolase. Flow cytometric analysis revealed that the neural stem cells were actively dividing and the percentage of cells in the S + G2/M phase was high. However, the ratio of cells in the S + G2/M phase decreased obviously as differentiation proceeded. Whole-cell patch-clamp re- cordings revealed apparent changes in potassium ion currents as the neurons differentiated. The potassium ion currents consisted of one transient outward potassium ion current and one delayed rectifier potassium ion current, which were blocked by 4-aminopyridine and tetraethylammonium, respectively. The experimental findings indicate that neural stem cells from newborn rat hippo- campus could be cultured and induced to differentiate into functional neurons under defined condi- tions in vitro. The differentiated neurons expressed two types of outward potassium ion cur'ents similar to those of mature neurons in vivo.
文摘The aim of this study was to compare the effects of d, l-Sotalol and dSotalol on the delayed rectifier K+ outward current in the presence of isoproterenol at different concentrations. Time-dependent delayed rectifier K+ outward currents were measured in isolated guinea pig single myocytes using the whole-cell configuration of the patch-clamp technique. Currents were measured in response to 300 ms depolarizing pulses from a holding potential of -40 mV in three experimental protocols [control, isoproterenol (10^(9)mol/L - 10^(-6) mol/L ), and isoproterenol (10^(-9)mol/L - 10^(-6)mol/L ) plus either d, l-Sotalol (10^(-4) mol/L) or d-Sotalol (10^(-4) mol/L)]. IK tail currents were measured upon repolarization to -40 mV. It was found that Ik was significantly amplified in the presence. of isoproterenol (10^(-9) mol/L- 10^(-6) mol/L) plus d-Sotalol. At 10-8 mol/L isoproterenol, Ik was increased by 92. 7%±17. 1 % (P<0. 05) and 54. 3 %±13. 4 % after d-Sotalol addition (P<0. 05). In contrast, d, l-Sotalol completely conteracted the increase of iK by isoproterenol (<10^(-8) mol/L), and compared to control, Ic was decreased by 35. 6 % ±8. 1% at 10^(-8) mol/L isoproterenol plus d, l-Sotalol (P<0. 05). It is concluded that the β-adrenergic blocking property of d, l-Sotalol but not that of dSotalol maintains the delayed rectifier K+ outward current blockade in the presence of isoproterenol in guinea pig myocytes. This might contribute to a superior antiarrhythmic efficacy as compared to d-Sotalol.
文摘The transmural heterogeneous changes of transient outward potassium currents (Ito) in rabbit hypertrophic cardiaomyocytes and the effects of long-term prophylactic treatment with volsartan were investigated. Rabbits were divided into hypertrophy group (left ventricular hypertrophy induced by partial ligation of abdominal aorta), vol-treated group (volsartan was administrated after the ligation), and control group (sham operated). Myocytes were isolated by a two-step enzymatical method. The sub-endocardial (Endo) and sub-epicardium (Epi) tissues were separated from midmyocardium (Mid) with a razor. Whole-cell patch-clamp technique was used to record potassium currents. The results showed that membrane capacitance was larger in hypertrophic cells than those in control and vol-treated cells (P<0.01 vs control cells, n=30). The densities of Ito in hypertrophic cells were reduced by sub-epicardium (Epi) (27.8±2.9) %, midmyocardium (Mid) (41.0±4.7) %, and sub-endocardium (Endo) (20.3±3.4) % compared with those in control cells. The decrease of Ito density was more pronounced in Mid than in Epi and Endo (P<0.01 vs Epi or Endo). There were no significant differences in Ito densities between vol-treated group and control group in three layers separately. In conclusion, volsartan can inhibit the transmural heterogeneous changes of Ito in left ventricular hypertrophic cardiomyocytes in rabbit.
基金the National Natural Science Foundation for Youth, No. 30400483
文摘We used RNA interference (RNAi) to disrupt synthesis of the cortical neuronal y-aminobutyric acid A receptor (GABAAR) al in rats during development, and measured outward K+ currents during neuronal electrical activity using whole-cell patch-clamp techniques. Three pairs of small interfering RNA (siRNA) for GABAAR al subunit were designed using OligoEngine RNAi software. This siRNA was found to effectively inhibited GABAAR al mRNA expression in cortical neuronal culture in vitro, but did not significantly affect neuronal survival. Outward K^currents were decreased, indicating that GABAAR al subunits in developing neurons participate in neuronal function by regulating outward K+ current.
文摘To elucidate the mechanism of arrhythmia in healed myocardial infarction (HMI), the changes of action potential duration (APD), transient outward potassium current (I to), delayed rectifier potassium current (I K) and inward rectifier potassium current (I K1) of left ventricular myocytes in non-infarcted zone of HMI were investigated. Rabbits were randomly assigned into two groups: HMI group, in which animals were subjected to thoracotomy and ligation of the circumflex coronary and sham-operated group, in which rabbits underwent thoracotomy but no conorary ligation. 3 months after the operation, the whole myocyte patch clamp technique was used to record APD, I to, I K, and I K1 of ventricular myocytes in non-infarcted zone.Our results showed that the membrane capacitance was larger in HMI group than in sham-operated group. Action potential duration was significantly lengthened in HMI group and early afterdepolarization (EAD) appeared in HMI group. The densities of I to, I K, tail, and I K1 were reduced significantly in HMI group, from 6.72±0.42 pA/pF, 1.54±0.13 pA/pF and 25.6±2.6 pA/pF in sham-operated group to 4.03±0.33 pA/pF, 1.14±0.11 pA/pF and 17.6 ±2.3 pA/pF, respectively. It is concluded that the reduced densities of I to , I K, tail and I K1 in ventricular myocytes of non-infarcted zone in HMI were responsible for the prolongation of APD and the presentation of EAD which played important roles in the development of malignant arrhythmia in HMI.
文摘Objective:To study the effect of lycium barbarum polysaccharides (LBP) on high glucose-induced retinal ganglion cell apoptosis, gene expression and delayed rectifier potassium current.Methods: RGC-5 retinal ganglion cell lines were cultured and divided into control group, high glucose group and LBP group that were treated with normal DMEM, high-glucose DMEM as well as high-glucose DMEM containing 500 ng/mL LBP respectively. After treatment, the Annexin V-FITC/PI kits were used to measure the number of apoptotic cells, fluorescence quantitative PCR kits were used to determine the expression of apoptosis genes and antioxidant genes, and patch clamp was used to test delayed rectifier potassium current. Results:12, 24, 36 and 48 h after intervention, the number of apoptotic cells of high glucose group was significantly higher than that of control group, and the number of apoptotic cells of LBP group was significantly lower than that of high glucose group (P<0.05);24 and 48 h after intervention, c-fos, c-jun, caspase-3, caspase-9, Nrf-2, NQO1 and HO-1 mRNA expression as well as potassium current amplitude (IK) and maximum conductance (Gmax) of high glucose group were significantly higher than those of control group while half maximum activation voltage (V1/2) was significantly lower than that of control group (P<0.05);c-fos, c-jun, caspase-3 and caspase-9 mRNA expression as well as IKand Gmaxof LBP group were significantly lower than those of high glucose group, while Nrf-2, NQO1 and HO-1 mRNA expression as well as V1/2 of LBP group were significantly higher than those of high glucose group (P<0.05).Conclusions:LBP can reduce the high glucose-induced retinal ganglion cell apoptosis and inhibit the delayed rectifier potassium current amplitude.
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.
基金The project was supported by a grant from the National Natural Sciences Foundation of China (No. 30271500)
文摘To investigate the effect of intedeukin-1β (IL-1β) on IA and IK currents in cultured murine trigeminal ganglion (TG) neurons, whole-cell patch clamp technique was used to record the IA and IK currents before and after 20 ng/mL IL-1β perfusion. Our results showed that 20 ng/mL IL-1β inhibited IA currents (18.3±10.7)% (n=6, P〈0.05). IL-1β at 20 ng/mL had no effect on G-V curve of IA but moved the H-infinity curve V0.5 from -36.6±6. 1 mV to-42.4±5.2 mV (n=5, P〈0.01). However, 20 ng/mL IL-1β had effect on neither the amplitude nor the G-V curve of IK. IL-1β was found to selectively inhibit IA current in TG neurons and the effect may contribute to hyperalgesia under various inflammatory conditions.
文摘A new method for the determination of aniline in environmental water based on oscillopolarographic titration was presented in this paper. Several factors including the kind, concentration, and volume of acid, the dosage of potassium bromide, the temperature and concentration of concomitant substances were investigated in detail. The experimental results indicated that this method was simple, rapid, and sensitive. The linear range was 8.367 × 10(?4) to 2.789 × 10(?2) mol L(?1), the relative standard deviation (R.S.D.) was lower than 0.96%, and the spiked recoveries of aniline in environmental water samples were in the range of 99.4–106.9% under the optimal conditions. The results indicated that the present method could be used as an alternative method for aniline determination in realworld water samples.
文摘The current difference between male and female rabbit ventricular myocytes was investigated for elucidating the mechanism of longer QT interval and higher incidence of drug-associated torsade de pointes in female rabbits than in male rabbits. Whole cell patch clamp technique was used to record APD, I_to, I_K,tail, I_K1 and I_Ca,L of myocytes from left ventricular apex. There was no difference in the membrane capacitance between male and female rabbit myocytes. APD_90 was longer in female rabbits (560.4±26.5 ms, n=15) than in male ones (489.0±20.7 ms, n=14), P<0.05. In female rabbit myocytes, I_K,tail, I_to, I_K1 and I_Ca,L were 0.71±0.05 pA/pF (n=17), 8.28±1.03 pA/pF (n=18), 24.5±3.6 pA/pF (n=12) and 9.0±2.3 pA/pF (n=15) respectively. In male rabbit myocytes, they were 0.84±0.07 pA/pF (n=18), 8.60±1.20 pA/pF (n=18), 25.9±4.5 pA/pF (n=14) and 9.3±2.6 pA/pF (n=16) respectively. I_K,tail in female rabbits was significantly lower than that of male rabbits (P<0.05), but there was no difference in I_to, I_K1 and I_Ca,L between male rabbits and female rabbits (P>0.05). The lower I_K,tail of female rabbit myocytes may contribute to the longer repolarization and the higher incidence of drug-associated torsade de pointes.
文摘Many rat taste receptor cells conduct action potentials(APs).APs had a mean threshold of -35 mV(n=95 cells)and a spike height of 52mV above threshold in current clamp(hold= -80mV).Aps could be classified into two significantly different (P<0.001) groups-fast,with short half-time durations and large outward currents (mean1.3 ms and 2.7nA),and slow,with long duration and small outward currents(mean9.2ms and 0. 29nA).AP upstrokes were conducted by TTX-sensitive sodium currents whereas the downstroke by TEA-blockable outward currents. Voltage dependent analysis of outward current separated transient and sustained components.The transient component was specifically blocked by 4-AP(1mmol/L).A calcium-dependent outward component was also revealed modulating voltage and external calcium concentration.The fast recovery phase of the AP appears related the sustained outward current whereas the after hyperpolarization(AHP) was blocked by 4AP suggesting a significant contribution of the transient component.Forskolin (FSK),which elevates cAMP,reversibly blocked the majority of the sustained current without influencing the transient. FSK greatly exaggerated the AHP without changing the spike height or duration. These data suggest that several components of the outward current contribute specifically to the gustatory AP and that the AP may be modulated by cyclic nucleotides.
基金Supported by National Natural Science Foundation of China(No. 60674111)
文摘Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field,and the characteristics of transient outward K+ channel were studied using the whole-cell patch-clamp technique.The experiment revealed that the amplitude of transient outward potassium channel current was reduced.The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12,P<0.01) respectively.The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current.Due to the magnetic field exposure,the half-activation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12,P<0.05) ,and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12,P<0.05) .The half-inactivation voltage of the inactivation curves also changed from-56.09±0.89 mV to-57.16±1.10 mV(n=12,P>0.05) and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12,P<0.05) .The results show that the static magnetic field can change the characteristics of transient outward K+ channel,and affect the physiological functions of neurons.
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Support from the Australian Research Council through a Discovery project (DP170102406)Future Fellowship project (FT150100109)+1 种基金Auto CRC 2020 (Project 1-117)funded by an Australian Research Council grant (LE0237478)
文摘Engineering design of battery configurations and new battery system development are alternative approaches to achieve high performance batteries. A novel flexible and ultra-light graphite anode is fabricated by simple friction drawing on filter paper with a commercial 8 B pencil.Compared with the traditional anode using copper foil as current collector, this innovative current-collector-free design presents capacity improvement of over 200% by reducing the inert weight of the electrode. The as-prepared pencil-trace electrode exhibits excellent rate performance in potassium-ion batteries(KIBs), significantly better than in lithium-ion batteries(LIBs), with capacity retention of 66% for the KIB vs. 28% for the LIB from 0.1 to 0.5 A g^(-1). It also shows a high reversible capacity of ~230 mAh g^(-1) at 0.2 A g^(-1), 75% capacity retention over350 cycles at 0.4 A g^(-1)and the highest rate performance(based on the total electrode weight) among graphite electrodes for K+ storage reported so far.