【摘要】 目的应用不同的起搏离子流通道阻断剂,观察If、IK和ICa.T在自律性活动中的作用,以比较它们作用的大小。方法细胞内微电极技术记录兔心窦房结细胞自律性动作电位,研究它们对自律性活动的影响。结果用E4031(1μmol/L)阻断钾通道,窦房结自律活动减慢45.4%;Cs(2 mmol/L)阻断If通道后,心率减少26.8%;N i(100μmol/L)阻断T型钙通道后,自律活动减少14.3%。联合运用2种通道阻断剂,留下所观察的通道,得出类似的结果。结论对窦房结细胞起搏作用大小的次序为IK、超极化激活的起搏离子流If和T型钙通道电流ICa.T。更多还原

【Abstract】 AIM To compare the contributions of delayed rectifier potassium current(I_k),hyperpolarized-activated current(I_f) and T-type calcium current(I_Ca·T) to the spontaneous depolarization during phase 4 in sinus node cells.METHODS The specific channel blockers were used in the perfused Tyrode′s solution.Conventional microelectrode technique was used to record the spontaneous action potential of rabbit sinus node cells.RESULTS E-4031 1 μmol/L(I_k blocker),CsCl 2 mmol/L(I_f blocker) and NiCl₂100 μmol/L(I_Ca·T block) decreased the heart rate by 45.3%,26.8% and 14.3% respectively.The use of two-blocker-method showed the same results.CONCLUSION The contributions of three major pacemaker currents to the spontaneous depolarization of SN cells are in the order of: I_k,I_f and I_{Ca ·T}.更多还原