缺血预适应对犬在体三层心肌单向动作电位和不应期的影响

探讨缺血预适应(IPC)抗急性缺血心律失常的部分电生理机制。12只犬随机分为对照组(n=6)和IPC组(n=6),采用特制电极记录和测量三层心肌单相动作电位(MAP)及有效不应期(ERP),测量并分析MAP时程(MAPD),MAPD跨室壁离散(TDR)及ERP跨室壁离散(TDE)。结果:对照组缺血时MAPD缩短,ERP延长且三层心肌延长的幅度不一致,IPC组缺血时MAPD缩短与ERP延长均不明显,两者相比具有显著差别(P<0.05)。两组三层心肌之间的MAPD变化一致,不存在TDR,对照组缺血时ERP变化明显不一致,TDE增大,与IPC组相比较具有显著差别(P<0.05或<0.01)。结论:IPC减少急性缺血时MAPD缩短、ERP延长及TDE,这可能是其抗心律失常的部分机制。

Effect of Ischemic Preconditioning on Monophasic Action Potential and Refractory of Three Layers Myocardium of Canine in Vivo

To investigate a part of the electrophysiological mechanism by which ischemic preconditioning (IPC) protects against arrhythmias induced by acute ischemia, twelve-canines were divided into two groups randomly: control (acute ischemia) group and IPC (a single 5 min occlusion and 10 min reperfusion followed by acute ischemia) group. With the monophasic action potential (MAP) technique, MAP and effective refractory period (ERP) of three layers myocardium were measured by specially designed plunge-needle electrodes and the transmural dispersion of repolarization (TDR) and transmural dispersion of ERP (TDE) were analyzed. Results: In control group, MAP duration shortened but ERP lengthened in differen t altitude during ischemia. In IPC group, the changes of MAP duration and ERP were not obvious. Among of three layers myocardium, MAP duration was the same in two groups. In control group, compared with IPC group MAP duration and ERP were diff erent obviously and TDE increased during acute ischemia. Conclusion: IPC can reduce both MAP duration shortening and ERP lengthening accompanied with TDE during acute ischemia, which may be a part of the electrophysiological mechanism by whi ch IPC protects against the arrhythmias induced by acute ischemia.