降钙素基因相关肽对家兔离体窦房结电生理活动的影响

Electrophysiological effects of calcitonin gene-related peptide on isolated sinoatrial node of the rabbit

用常规微电极方法研究了降钙素基因相关肽 (CGRP)对家兔窦房结起搏细胞的电生理作用 ,并进一步探讨这种作用与钙电流的关系。结果 :( 1)低浓度CGRP ( 1nmol/L)对窦房结动作电位各参数无显著影响 ;中等浓度CGRP ( 10nmol/L)可增加最大舒张期电位、动作电位幅度、0期最大除极化速率和 4期自动除极速率 ,缩短窦性周期、动作电位复极化 5 0 %和 90 %时间 ,这些作用经 2 0min达到高峰 ;高浓度CGRP ( 10 0nmol/L)可引起窦房结节律失常。 ( 2 )钙拮抗剂CdCl2 和verapamil可削弱由CGRP ( 2 0nmol/L)引起的窦房结细胞动作电位改变 ,结果提示 。

The purpose of this study was to investigate the electrophysiological effects of calcitonin gene related peptide (CGRP) on the pacemaker cell of rabbit sinoatrial node (SAN) and to determine whether I Ca is involved in the effects. Action potentials (AP) were recorded from the isolated SAN with microelectrode technique. It was found: (1) CGRP (1 nmol/L) had no effect on AP configuration; CGRP (10 nmol/L) increased the maximal diastolic potential, AP amplitude and depolarization velocity of 0 and 4 phases, and decreased sinus cycle length and AP duration. After applying CGRP for 20 min the above effects reached to a maximum. (2) CGRP (100 nmol/L) caused arrhythmia in the SAN. (3) Calcium channel antagonists, CdCl 2 and verapamil attenuated the electrophysiological changes in AP of SAN induced by CGRP (20 nmol/L). The results indicate that a calcium dependent mechanism may underlie the CGRP effects.