Na+/Ca2+ exchanger current and K+ current remodeling in midmyocardial cells of hypertrophic left ventricle]

OBJECTIVE: To investigate the characteristics of Na+/Ca2+ exchanger current (INa+ /Ca2+) and K+ current remodeling in midmyocardial cells of hypertrophic left ventricle for understanding the ionic basis of arrhythmia of the hypertrophic heart. METHODS: Twenty New Zealand rabbits were divided equally into normal control group and operation group, and in the latter, left ventricular hypertrophy was induced in the rabbits by partial ligation of the abdominal aorta. Action potentials, INa+/Ca2+, slowly activating delayed rectifier K+ current (IKs) and rapidly activating delayed rectifier K+ current (IKr) were recorded in the two groups by using whole-cell patch-clamp technique. RESULTS: At the basic cycle length of 2 s, 90% action potential duration (APD90) in control and operation groups was 522.0+/-19.5 ms (n=6) and 664.7+/-32.7 ms (n=7) respectively; at the testing potential of +40 mV, outward INa+/Ca2+ density in the two groups was 0.94+/-0.11 pA/pF (n=9) and 1.30+/-0.11 pA/pF (n=8) respectively; the testing potential of -100 mV elicited inward INa+/Ca2+ density of 0.40+/-0.05 pA/pF (n=9) and 0.56+/-0.02 pA/pF (n=8) respectively. The testing potential of +50 mV induced IKs tail current density of 0.26+/-0.03 pA/pF (n=8) and 0.17+/-0.01 pA/pF (n=9), and IKr tail current density of 0.34+/-0.02 pA/pF (n=8) and 0.23+/-0.02 pA/pF (n=9) respectively. Statistically significant differences were identified between the control and operation groups in all the above indices measured. CONCLUSION: The characteristics of electrical remodeling changes in midmyocardial cells of hypertrophic left ventricle, exhibited by prolonged action potential, up-regulated INa+/Ca2+ and down-regulated IKs and IKr.     

大鼠海马神经干细胞外向电压门控性钾通道的电生理特性

目的 研究大鼠海马源神经干细胞(NSC)外向电压门控性钾通道(Kv)的电生理特性.方法 利用无血清培养、单细胞克隆技术,体外培养SD大鼠海马组织源NSC.以免疫细胞化学方法对NSC及其分化后的子代神经细胞进行鉴定.应用膜片钳技术全细胞模式记录不同外向Kv通道的电生理特性.结果 体外培养SD大鼠海马组织源NSC表达巢蛋白(nestin),在体外可诱导分化产生分别表达Tuj1和GFAP的细胞.全细胞膜片钳可记录到三种外向Kv通道:一种缓慢激活的、对四乙基胺(TEA)敏感的延迟整流钾电流(IDR);一种快速激活和失活、可被4-氨基吡啶(4-AP)阻断的外向瞬时钾电流(IA),其在+20 mV和+50 mV的电流密度分别为11 pA/pF±3 pA/pF和29 pA/pF ±7 pA/pF(标本数=11);一种可被iberiotoxin(IbIX)抑制的大电导钙激活钾通道(BKCa),钳制电位+80mV时,加入100 nM IbTX前后的电流密度分别为56 pA/pF ±4 pA/pF和45 pA/pF±4 pA/pF(标本数=6.P＜0.05).结论 体外培养的未分化状态下SD大鼠海马源NSC至少含有IDR、IA和BKCa三种外向Kv通道.     

Cardioprotective effects of simvastatin on reversing electrical remodeling induced by myocardial ischemia-reperfusion in normocholesterolemic rabbits

Background Recent studies have revealed that pretreatment with statin is effective in preventing arrhythmia, but its electrophysiological mechanism is unclear. This study was conducted to investigate the cardioprotective effects of simvastatin on reversing electrical remodeling in left ventricular myocytes of rabbit heart undergoing ischemia-reperfusion, so as to explore the ionic mechanism responsible for the anti-arrhythmic effect of statin. Methods Forty-five rabbits were randomly divided into three groups： ischemic-reperfusion group （I-R）, simvastatin intervention group （Statin） and sham-operated control group （CON）. Anesthetized rabbits were subjected to 30-minute ischemia by ligation of the left anterior descending coronary artery and a 60-minute reperfusion after a 3-day administration of oral simvastatin of 5 mg-kg^-1.d^-1 in the Statin group or a placebo in the I-R group. Single ventricular myocytes were isolated enzymatically from the epicardial zone of the infracted region dedved from the hearts in the I-R and Statin group and the same anatomical region in the CON animals. The whole cell patch-clamp technique was used to record membrane ionic currents, including sodium current （IRa）, L-type calcium current （Ica-L） and transient outward potassium current （Ito）. Simultaneously, the level of serum cholesterol was examined. Results There was no significant difference in the serum cholesterol concentration among the three groups. The peak IRa current density （at -30 mV） was significantly decreased in I-R （（22.46±5.32） pA/pF, n=12） compared with CON （（42.78±5.48） pA/pF, n=16, P〈0.01） and Statin （（40.66±5.89） pA/pF, n=15, P〈0.01）, while the peak IRa current density in the Statin group was not different from CON （P〉0.05）. The peak ICa-L current density （at 0 mV） was significantly increased in I-R （（4.34±0.92） pA/pF, n=15） compared with CON （（3.13±1.22） pA/pF, n=13, P〈0.05） and Statin （（3.46±0.85） pNpF, n=16, P〈0     

维拉帕米对链脲佐菌素诱导糖尿病大鼠心肌缺血再灌注损伤的影响及机制

目的 观察维拉帕米(Ver)对糖尿病大鼠心肌缺血再灌注(L/R)后心功能,细胞内[Ca2+]i及L-型钙电流(ICa-L)影响,探讨其防治糖尿病心肌I/R损伤的作用和机制.方法 链脲佐菌素诱导糖尿病大鼠后的第6～14周龄给予Ver(8 mg·kg-1·d-1)灌胃,Langendorff系统复制大鼠心肌I/R模型,观察不同实验组的心功能变化,双酶法急性分离各组心肌细胞,激光扫描共聚焦显微镜加Fluo-3/AM荧光染色技术和全细胞膜片钳技术分别观察心肌细胞内Ca2+荧光强度和ICa-L大小.结果 (1)与糖尿病组相比,Ver糖尿病组的左心室发展压(91.3±4.6)mm Hg(1 mm Hg=0.133kPa)、舒张末压(1535±280)mm Hg、收缩压最大上升速率(5833±256)mm Hg/s、冠状动脉流量(13.7±0.9)ml/min均明显增加(P<0.01),收缩压最大下降速率(3504±319)mm Hg/s明显减少(P<0.01).(2)Ver糖尿病组心肌细胞内Ca2+荧光强度(155.6±10.9)nmol/L与糖尿病组(245.2±17.5)nmoL/L相比明显减弱(P<0.01).(3)当指令电位为+20 mV时,Ver糖尿病组心肌细胞ICa-L为(-6.81±0.76)pA/pF,与正常对照组[(-8.17±2.07)pA/pF]相比减小(P<0.05),与糖尿病组[(-3.21±0.54)pA/pF]相比增加(P<0.01),与Ver对照组[(-7.14±2.17)pA/pF]相比减少(P>0.05).Ver糖尿病组的I-V曲线显著低于糖尿病组,最大峰值在+20 mV.结论 Ver可以明显改善I/R损伤引起的糖尿病大鼠心功能下降,其机制可能是Ver调控心肌细胞膜上ICa-L内流大小,优化心肌细胞内[Ca2+]i平衡,避免I/R时心肌细胞内Ca2+超载.     

通络药物对心肌细胞钠钙离子通道的影响

目的观察通络药物参松养心胶囊提取干粉溶液对单个豚鼠J0室肌细胞膜钠通道电流（INa）、L型钙通道电流（ICa,L）的影响。方法用钙外液将参松养心胶囊干粉配制成不同浓度（1％、0．5％、0．25％）。用酶解法分离单个心室肌细胞,并用全细胞膜片钳记录技术记录电流。结果当药物浓度0．5％时,可以使INA峰值电流密度从（27．2±5．4）pA／pF降至（14．9±2．8）pA／pF,平均抑制率为44．8％±7．7％（n=5,P〈0．05）;药物浓度为1％,0．5％,0．25％时,分别对ICa,L的峰值电流密度的抑制率为50．7％±5．6％,44．8％±6．5％,和19．2％±1．1％,（n=5,P〈0．05）。药物可以使INA、ICa,L的电流密度-电压曲线上移,但均不改变其激活、峰值和反转电位。结论参松养心胶囊提取干粉溶液对,INA、ICa,L具有阻滞作用,这可能是其抗心律失常和心肌保护作用药理机制的一部分。     

产前应激对子代大鼠海马CA3区神经元高电压激活Ca2+通道动力学特征的影响

目的探讨产前应激对子代大鼠海马CA3神经元高电压激活(HVA)钙通道动力学特征的影响。方法给予孕鼠束缚应激,急性分离子代海马CA3神经元,应用全细胞膜片钳技术,研究产前应激对子代大鼠海马CA3区神经元高电压激活Ca2 通道的影响。结果产前应激增加了子代海马CA3神经元高电压激活钙电流幅值、电流面积,而未改变其电导-电压关系、稳态失活动力学、时间到峰等指标。对照组和产前应激组子代海马CA3神经元高电压激活最大钙电流幅值分别为(-40.89±0.31)pA/pF和(-49.44±0.37)pA/pF(P<0.01)。最大电流面积分别为(106.81±4.20)nA*ms和(133.49±2.59)nA*ms(P<0.01)。结论在胎儿发育的关键时期,给予母体应激,对子代海马神经元离子通道产生持续的影响。     

Electrophysiological properties of delayed rectifier outward K+ currents in the differentiation and development of hippocampal neural stem cells

OBJECTIVE: To study the developmental electrophysiological properties of delayed rectifier outward K+ currents (IDR) in undifferentiated NSC and NSC-derived neurons at various time points of adult SD rat hippocampus in vitro. METHODS: Neural stem cells were isolated from the hippocampus of adult SD rats with serum-free incubation and single-cell cloning technique. Electrophysiological recordings of IDR were performed using whole-cell patch clamp. RESULTS: The current density of IDR increased in NSC-derived neurons DIV 0-6 d whereas remained constant in DIV > 6 d. The current density of IDR at +50 mV was 45 pA/pF +/- 4 pA/pF and 56 pA/pF +/- 10 pA/pF in undifferentiated NSCs and NSC-derived neurons DIV 0-6 d respectively (n = 9). The activation process of IDR was also altered in DIV 0-6 d whereas remained constant in DIV > 6 d. The positive shift in steady-state activation curve of IDR revealed an increase of V1/2, however the slope factors K remained unchanged. V1/2 was 9 mV +/- 3 mV and 12 mV +/- 3 mV in undifferentiated NSCs and NSC-derived neurons DIV 0-6 d respectively (n = 9, P < 0.05). The inactivation properties of IDR were not altered before and after differentiation. CONCLUSION: Electrophysiological characteristics of IDR were all altered in DIV 0-6 d, suggesting the essential role of IDR in neurogenesis and early stage of differentiation/development process is very important for the functional mature of neuron.     

EFFECTS OF GLIBENCLAMIDE, GLIMEPIRIDE, AND GLICLAZIDE ON ISCHEMIC PRECONDITIONING IN RAT HEART

Objective To compare the influence of different sulfonylureas on the myocardial protection effect of ischemic preconditioning (IPC) in isolated rat hearts, and ATP-sensitive potassium channel current (IKATP) of rat ventricular myocytes. Methods Isolated Langendorff perfused rat hearts were randomly assigned to five groups: (1) control group, (2) IPC group, (3) IPC glibenclamide (GLB, 10 μmol/L) group, (4) IPC glimepiride (GLM, 10 μmol/L) group, (5) IPC gliclazide (GLC, 50 μmol/L) group. IPC was defined as 3 cycles of 5-minute zero-flow global ischemia followed by 5-minute reperfusion. The haemodynamic parameters and the infarct size of each isolated heart were recorded. And the sarcolemmal IKATP of dissociated ventricular myocytes reperfused with 10 μmol/L GLB, 1 μmol/L GLM, and 1 μmol/L GLC was recorded with single-pipette whole-cell voltage clamp under simulated ischemic condition. Results The infarct sizes of rat hearts in IPC (23.7%±1.3%), IPC GLM (24.6%±1.0%), and IPC GLC (33.1%±1.3%) groups were all significantly smaller than that in control group (43.3%±1.8%; P<0.01, n=6). The infarct size of rat hearts in IPC GLB group (40.4%±1.4%) was significantly larger than that in IPC group (P<0.01, n=6). Under simulated ischemic condition, GLB (10 μmol/L) decreased IKATP from 20.65±7.80 to 9.09±0.10 pA/pF (P<0.01, n=6), GLM (1 μmol/L) did not significantly inhibit IKATP (n=6), and GLC (1 μmol/L) decreased IKATP from 16.73±0.97 to 11.18±3.56 pA/pF(P<0.05, n=6). Conclusions GLM has less effect on myocardial protection of IPC than GLB and GLC. Blockage of sarcolemmal ATP-sensitive potassium channels in myocardium might play an important role in diminishing IPC-induced protection of GLM, GLB, and GLC.     

老年SD大鼠前列腺上皮细胞膜钾离子通道变化及意义

目的探讨雄性SD大鼠前列腺上皮细胞膜钾离子通道电流的变化和对钾通道阻断剂的反应。方法分别取3个月龄成年和12个月龄的老年SD大鼠的背外侧叶前列腺组织,剪成1—2mm^3大小,经消化、培养、免疫组鉴别,将形态正常、贴壁良好的腺上皮细胞用全细胞膜片钳模式记录钾通道电流。结果成年和老年SD大鼠的前列腺上皮细胞膜＋80mV钾电流密度分别为（10．84±1．54）pA／pF vs（18．48±1．7）pA／pF（n=20,P〈0．01）;钙激活型钾通道抑制剂（KCa通道）四乙胺（TEA）对老年大鼠峰电流阻断从19．1±2．9到7．2±3．2,KCa电流被抑制约63％;成年大鼠为9．5±1．8到5．4±3．1,KCa通道电流被抑制约44％。电压依赖型钾通道抑制剂4-AP（四氨基吡啶）对大鼠前列腺上皮细胞膜钾电流有显著阻断效应。结论老年大鼠的前列腺上皮细胞膜钾通道电流比成年大鼠显著增强,同时老年大鼠KCa通道电流对TEA更敏感。由此结果可推论老年大鼠的前列腺上皮细胞分泌功能是降低的。     

兔心肌梗死后右心室肌细胞离子通道电流的变化

目的探讨心肌梗死后右心室肌细胞离子通道电流的变化.方法该研究采用结扎兔冠状动脉左前降支的方法建立心肌梗死动物模型,应用膜片钳全细胞记录方法,记录心肌梗死后2个月右心室心肌细胞钠通道电流(INa)、L-钙通道电流(ICa-L)、瞬间外向钾电流(Ico)的变化.结果心肌梗死后2个月,心肌梗死组INa电流密度峰值[(20.42±1 73)pA/pF,n=15]较对照组[(35 40±3.43)pA/pF,n=16]明显下降(P＜0.05);心肌梗死组ICa-L电流密度峰值[(5.71±0.93)pA/pF,n=12]与对照组[(6.28±1.03)pA/pF,n=10]略下降,但无明显差异(P＞0.05);心肌梗死组Ito电流密度( 60 nV时)[(8.61±0.95)pA/pF,n=16]较对照组[(14.38±1.24)pA/pF,n=17]明显下降(P＜0.05).结论心肌梗死可引起右心室肌细胞INa和Ito的下降,造成心肌传导速度下降和动作电位时程相对延长、复极异常,可能是导致心肌梗死后出现室性心律失常的离子机制.     

Effects of Chinese herbs on multiple ion channels in isolated ventricular myocytes

Background Shensong Yangxin (SSYX) is one of the compound recipe of Chinese materia medica. This study was conducted to investigate the effects of SSYX on sodium current (I(Na)), L-type calcium current (I(Ca,L)), transient outward potassium current (I(to)), delayed rectifier current (I(K)), and inward rectifier potassium currents (I(K1)) in isolated ventricular myocytes. Methods Whole cell patch-clamp technique was used to study ion channel currents in enzymatically isolated guinea pig or rat ventricular myocytes. Results SSYX decreased peak I(Na) by (44.84±7.65)% from 27.21±5.35 to 14.88±2.75 pA/pF (n=5, P&lt;0.05). The medicine significantly inhibited the I(Ca,L). At concentrations of 0.25, 0.50, and 1.00 g/100 ml, the peak I(Ca,L) was reduced by (19.22±1.10)%, (44.82±6.50)% and (50.69±5.64)%, respectively (n=5, all P&lt;0.05). SSYX lifted the I-V curve of both I(Na) and I(Ca,L) without changing the threshold, peak and reversal potentials. At the concentration of 0.5%, the drug blocked the transient component of I(to) by 50.60% at membrane voltage of 60 mV and negatively shifted the inactive curve and delayed the recovery from channel inactivation. The tail current density of I(K) was decreased by (30.77±1.11)% (n=5, P&lt;0.05) at membrane voltage of 50 mV after exposure to the medicine and the time-dependent activity of I(K) was also inhibited. Similar to the effect on I(K), the SSYX inhibited I(K1) by 33.10% at the test potential of –100 mV with little effect on reversal potential and the rectification property. Conclusions The experiments revealed that SSYX could block multiple ion channels such as I(Na) I(Ca,L), I(k), I(to) and I(K1), which may change the action potential duration and contribute to some of its antiarrhythmic effects.     

敲除Annexin A7基因的小鼠早期胚胎心肌细胞钙稳态正常

目的:研究Annexin A7在早期胚胎发育过程中对钙平衡调节的作用. 方法: 利用钙成像技术和膜片钳技术检测敲除Annexin A7小鼠的早期胚胎心肌细胞的钙平衡以及相应的离子通道的特性. 结果: 在胚胎心肌细胞发育的早期,敲除Annexin A7小鼠胚胎心肌细胞的静息钙(340/380荧光比例 0.78±0.02)、钙峰值(340/380荧光比例1.28±0.05)和正常细胞的值相似;动作电位(APD90 242.7±43.7 ms、最大去极化电位56.8±1.7 mV)以及L-型钙电流密度(14.1±2.5 pA/pF)和正常细胞的相似,并且钙电流能被碳酰胆碱减小(51.7±8)%,也和正常细胞相似. 结论: 敲除Annexin A7基因的小鼠早期胚胎心肌细胞具有正常的钙稳态以及正常的离子通道.     

Effect of didrovaltrate on l-calcium current in rabbit ventricular myocytes

OBJECTIVE:To investigate the effect of didrovaltrate on L-type calcium current(I Ca-L) in rabbit ventricular myocytes.METHODS:We used the whole cell patch clamp recording technique.RESULTS:Didrovaltrate at concentrations of 30 μg/L and 100 μg/L significantly decreased peak I Ca-L(I Ca-Lmax) from(6.01±0.48) pA/pF to(3.45±0.27) pA/pF and(2.16 ± 0.19) pA/pF(42.6% and 64.1%,n=8,P< 0.01),respectively.Didrovaltrate shifted upwards the current-voltage curves of I Ca-L without changing their active,peak and reverse potentials.Didrovaltrate affected the steady-state inactivation of I Ca-L.The half activation potential(V 1/2) was significantly shifted from(-26 ± 2) to(-36 ± 3) mV(n=6,P<0.05),with a significant change in the slope factor(k)(from 8.8 ± 0.8 to 11.1 ± 0.9,n=6,P<0.05).Didrovaltrate did not affect the activation curve.CONCLUSION:Didrovaltrate blocks I Ca-L in a concentration-dependent manner and probably inhibits I Ca-L in its inactive state,which may contribute to its cardiovascular effect.     

The effects of paeoniflorin monomer of a Chinese herb on cardiac ion channels

Background  Because of the potential proarrhythmic effect of current antiarrhythmic drugs, it is still desirable to find safer antiarrhythmic drugs worldwide. Paeoniflorin is one of the Chinese herb monomers that have different effects on many ion channels. The present study aimed to determine the effects of paeoniflorin on cardiac ion channels.

Methods  Whole-cell patch-clamp technique was used to record ion channel currents. L-type calcium current (I_Ca-L), inward rectifier potassium current (I_K1), and transient outward potassium current (I_to1) were studied in rat ventricular myocytes and sodium current (I_Na), slow delayed rectifier current (I_Ks), and HERG current (I_Kr) were investigated in transfected human embryonic kidney 293 cells.

Results  One hundred μmol/L paeoniflorin reduced the peak I_Ca-L by 40.29% at the test potential of +10 mV (from (–9.78±0.52) pA/pF to (–5.84±0.89) pA/pF, n=5, P=0.028). The steady-state activation curve was shifted to more positive potential in the presence of the drug. The half activation potentials were (–11.22±0.27) mV vs. (–5.95±0.84) mV (n=5, P=0.007), respectively. However, the steady-state inactivation and the time course of recovery from inactivation were not changed. One hundred μmol/L paeoniflorin completely inhibited the peak I_Na and the effect was reversible. Moreover, paeoniflorin inhibited the I_K1 by 30.13% at the test potential of –100 mV (from (–25.26±8.21) pA/pF to (–17.65±6.52) pA/pF, n=6, P=0.015) without effects on the reversal potential and the rectification property. By contrast, 100 μmol/L paeoniflorin had no effects on I_to1, I_Ks or I_Kr channels.

Conclusions  The study demonstrated that paeoniflorin blocked I_Ca-L, I_Na, and I_K1 without affecting I_to1, I_Ks, or I_Kr. The multi-channel block effect may account for its antiarrhythmic effects with less proarrhythmic potential.

     

肾上腺髓质素对脓毒性休克大鼠心肌细胞外向钾电流的影响

目的 研究肾上腺髓质素(ADM)对脓毒性休克大鼠心肌细胞外向钾电流的影响.方法 成年大鼠腹腔注射脂多糖(LPS,10 mg/kg)4 h后,分离心室肌细胞.用全细胞膜片钳的方法 记录瞬时外向钾电流(I_(to)),稳态钾电流(I_(ss))和ATP敏感钾电流(I_(K,ATP)).结果 LPS处理对I_(to)和I_(ss)无影响.休克心肌细胞I_(K,ATP)密度[(2.66 ± 0.56)pA/pF(n=12)]较正常心肌细胞值[(0.27 ± 0.08)pA/pF(n=14)]明显增加(P＜0.01).ADM受体拮抗剂ADM-(22-52)可使增加的I_(K,ATP)得到明显的恢复[(0.69 ± 0.21)pA/pF(n=11),P＜0.01 vs LPS 组].而ADM-(22-52)与100 μmol/L氨基胍联合处理几乎可完全取消I_(K,ATP)的增加.结论 脓毒性休克大鼠心肌细胞I_(K,ATP)被激活.ADM 与NO共同参与了脓毒性休克大鼠心肌细胞I_(K,ATP)的激活.     

心力衰竭患者抗β1肾上腺素能受体自身抗体阳性血清对心肌细胞L-型钙通道的影响

目的探讨心力衰竭患者抗β1肾上腺素能受体自身抗体(Abs)阳性血清对豚鼠心室肌细胞膜上L型钙电流(IGa-L)的影响.方法应用全细胞钳制技术,定量观察并比较β1肾上腺素能受体激动剂异丙肾上腺素(Iso)和心力衰竭患者Abs阳性血清对豚鼠单个心室肌细胞的ICa-L电流强度的影响.结果β1肾上腺素能受体激动剂Iso可使基础ICa-L峰值电流强度和标准电流密度从(997.09±227.5)pA和(8.20±0.86)pA/pF增大到(2 241.01±348.5)pA和(18.98±1.18)pA/pF(P＜0.01),而β1肾上腺素能受体阻滞剂艾司洛尔(Esm)可以阻断这一作用.同样,心力衰竭患者Abs阳性血清可使基础ICa-L峰值电流强度从(963.57±207.56)pA增大到(1 382.41±241.36)pA,标准电流密度从(8.14±0.72)pA/pF增大到(11.70±1.03)pA/pF(P＜0.01),Esm也可阻断此作用.结论人类心脏Abs阳性血清对心肌细胞受体有异丙肾上腺素样激动剂效应,可能参与了心力衰竭时心肌细胞的病理生理过程.     

海马神经干细胞体外诱导分化过程中延迟整流钾通道的电生理特性

目的 研究大鼠海马源神经干细胞(NSC)分化前及其体外诱导分化的神经元样细胞在不同发育阶段延迟整流钾电流(IDR)的电生理特性.方法 利用无血清培养、单细胞克隆技术,体外培养SD大鼠海马组织源NSC.应用膜片钳技术全细胞模式记录IDR的电生理特性.结果 IDR的电流密度在NSC分化前和体外分化(DIV)0～6 d分别为45 pA/pF±4 pA/pF和56 pA/pF±10 pA/pF(+50 mV,标本数=9),而在DIV＞6 d的发育过程中保持稳定;IDR的半数最大激活膜电位(V1/2)在NSC分化前和DIV 0～6 d分别为9 mV±3 mV和12 mV±3 mV(标本数=9,P＜0.05),激活曲线右移,斜率参数K值无明显改变,但IDR激活特性在DIV＞6 d的发育过程中无明显改变;IDR的失活特性NSC分化前后及不同发育阶段的神经元样细胞中均无改变.结论 NSC分化/发育过程中,IDR的特性改变均发生在DIV 0～6 d,提示IDR通道在神经发育过程中发挥作用,且发育初始阶段对于细胞功能的成熟尤为重要.     

肥厚左心室肌中层细胞Na+/Ca2+交换体电流及钾电流重构特征

目的 探讨肥厚左心室肌中层细胞Na⁺/Ca²⁺交换体电流(Na⁺/Ca²⁺ exchanger current,I_Na⁺/Ca²⁺)及钾电流重构特征,揭示心肌肥厚时心律失常发生的离子基础。方法 新西兰兔分为正常对照组及手术组各10只,手术组通过肾上腹主动脉次全缩窄诱发左室肥厚。采用全细胞膜片钳技术分别记录对照组及手术组左心室肌中层细胞的动作电位、I_Na⁺/Ca²⁺、慢激活的延迟整流钾电流(slowly activating delayed rectifier potassium current,I_Ks)、快激活的延迟整流钾电流(rapidly activating delayed rectifier potassium current,I_kr)等。结果 在基础刺激周长为2 s时,对照组和手术组的90%动作电位时程(90% action potential duration,APD90)分别为522.0±19.5 ms(n=6)、664.7±32.7 ms(n=7);在测试电位为+40 mV时,外向I_Na⁺/Ca²⁺密度在对照组及手术组分别为0.94±0.11 pA/pF(n=9)、1.30±0.11 pA/pF(n=8);在测试电位为-100 mV时,内向I_Na⁺/Ca²⁺密度在对照组及手术组分别为0.40±0.05 pA/pF(n=9)、0.56±0.02 pA/pF(n=8);在测试电位为+50 mV时,对照组及手术组的I_Ks尾电流密度分别为0.26±0.03 pA/pF(n=8),0.17±0.01 pA/pF(n=9);在测试电压为+50 mV时,对照组及手术组的I_kr尾电流密度分别为0.34±0.02 pA/pF(n=8),0.23±0.02 pA/pF(n=9),以上二者相比均有统计学意义。结论肥厚左心室肌中层细胞的电生理特性发生改变,表现为动作电位时间延长、I_Na⁺/Ca²⁺上调、I_Ks及I_kr下调。     

淫羊藿苷对兔心室肌细胞L-型钙电流的影响

目的:利用膜片钳技术研究淫羊藿苷(ICA)对兔单个心室肌细胞L-型钙电流(ICa,L)的影响。方法:采用酶解法分离兔单个心室肌细胞,应用全细胞膜片钳技术观察10,20,40μmol/L的ICA对心室肌细胞ICa,L的作用。结果:①10,20,40μmol/L的ICA使兔心室肌细胞ICa,L最大峰电流密度从(15.81±1.23)pA/pF分别降至(11.27±0.89)pA/pF,(9.48±0.85)pA/pF和(6.87±0.81)pA/pF(n=6,P<0.05),抑制率分别为28.7%,40.0%和56.5%;ICA使ICa,L的电流-电压曲线上移,但不改变其基本形状;②20μmol/L ICA可以使钙通道稳态失活曲线左移并可减慢L-型钙通道失活后的恢复过程。结论:ICA对ICa,L具有浓度依赖性阻滞作用,这可能是其抗心律失常的重要机制之一。     

Obestatin抑制胰岛β细胞株INS-1细胞L型钙通道电流

目的 观察obestatin对胰岛β细胞株INS-1细胞L型钙通道电流的影响.方法 应用穿孔全细胞膜片钳技术研究obestatin对培养的胰岛β细胞株INS-1细胞膜L型电压敏感钙通道电流（L-type calcium ion channel current,ICa.L）的影响.结果胰岛β细胞株INS-1细胞钳制膜电位为-20 mV时,分别给予胰岛β细胞株INS-1细胞0nM（对照组）和1、10、100nM obestatin灌流5min后,ICa,L峰值呈浓度依赖性降低,各组为给药前的（97±8）％、（91±7）％、（60±9）％和（45±6）％.其中,10nM和100nM obestatin灌流5min后ICa,L峰值与对照组相比显著减小（P＜0.0I,n=5）.胰岛β细胞株INS-1细胞钳制膜电位分别为-30、-20、-10和0mY时,给予10nM obestatin之前,其ICa,L峰值分别为（-5.48±0.69）、（-5.70±0.68）、（-5.58±0.61）和（-3.90±0.44） pA/pF,灌流10nM obestatin 5 min后,ICa,L峰值分别下降至（-3.11 ±0.68）、（-3.60±0.99）、（-3.26±1.03）和（-2.28±0.71）pA/pF,均明显低于obestatin给药前（P＜0.01,n=5）.结论 obestatin可抑制胰岛β细胞株INS-1细胞L型钙通道电流.