滇黄芩总黄酮对豚鼠心肌细胞电压依赖性钠通道电流的影响

Effects of Total Flavonoid from Scutellaria amoena on Voltage-dependent Na+Current in Guinea-pig Ventricular Myocytes

目的:研究滇黄芩总黄酮(totla flavonoid)对豚鼠心肌组织电压门控性钠通道的影响。方法:成年豚鼠,肝素抗凝后,腹腔麻醉,断头处死,迅速取其心脏,进行Langendorff灌流,先用无钙台式液灌流10 min,再以Ⅰ型胶原酶溶液灌流心脏,待心脏基本变软后剪取心室部分,制备单个心室肌细胞。分离出的豚鼠心肌单细胞,用全细胞电压钳技术记录电压依赖性钠电流进行研究。结果:滇黄芩总黄酮能可逆性抑制钠电流,其半数抑制浓度(IC50)为106 mg.L-1(95%的可信限是92～112 mg.L-1)。滇黄芩总黄酮并不影响钠通道激活开放的刺激电位阈值、最大激活电位值和反转电位值,但能使可激活开放的钠通道明显减少,钠离子电流明显衰减,可引出的钠电流在-40 mV处较正常组减少45.6%。细胞外给予滇黄芩总黄酮不影响钠通道激活曲线:对照组与106 mg.L-1的滇黄芩总黄酮组的半激活电压(V1/2)分别为(-50.4±1.7)mV和(-50.1±3.1)mV(n=6差异无统计学意义)。细胞外给予滇黄芩总黄酮可影响钠通道失活曲线,106 mg.L-1的滇黄芩总黄酮对电压依赖性稳态失活钠电流会引起一个大约12 mV的负向漂移,延缓失活钠通道的恢复:对照组与106 mg.L-1的滇黄芩总黄酮组的V1/2分别为(-69.4±1.6)mV和(-79.3±3.2)mV(n=7,P<0.05),两者间的差异有显著性意义,斜率分别为(-8.2±0.9)mV和(7.1±0.7)mV。细胞外给予滇黄芩总黄酮也可影响失活钠通道的恢复,使钠通道的复活时间常数显著延长:对照组和106mg.L-1的滇黄芩总黄酮组的时间常数分别为(15.6±6.3),(29.8±14.8)ms(n=6,P<0.05),差异有显著性意义。结论:滇黄芩总黄酮可阻滞豚鼠心肌细胞钠通道,是稳定的豚鼠心肌组织钠通道阻断剂。

Objective： To study the effects of total flavonoid from Scutellaria amoena on voltage-gated Na＋ channels in cardiac tissues. Method： Adult guinea-pigs were heparinized and then sacrificed by decapitation after being anesthetized.The heart was removed immediately, and the aorta of the isolated heart was connected to a Langendorff apparatus and perfused with Ca2＋-free Tyrode＇s solution for 10 min, and then with the same solution containing collagenase I.After dissociation and collection, cells were mechanically dispersed and single ventricular myocytes were enzymatically dissociated from adult guinea-pig heart.Voltage-dependent Na＋ current was recorded using whole cell voltage-clamp technique. Result： Total flavonoid reversibly inhibited Na＋ current with an IC50 value of 106 mg·L-1 （95% confidence range： 92-112 mg·L-1）.The inhibitory effects of total flavonoid on Na＋ current exhibited use-dependence.Total flavonoid at 106 mg·L-1 caused a negative shift （about 12 mV） in the voltage-dependence of steady-state inactivation of Na＋ current, and retarded its recovery from inactivation, but did not affect its activation curve. Conclusion： In addition to blocking other voltage-gated ion channels, total flavonoid can block Na＋ channels in guinea-pig ventricular myocytes.Total flavonoid acts as inactivation stabilizer of Na＋ channels in cardiac tissues.