大鼠左心房肌单相动作电位的增龄性变化

目的　研究年龄对大鼠左心房肌单相动作电位(monophasicactionpotential,MAP)的影响。方法　选取实验用Wistar大鼠4 0只,按出生年龄分为青年组、成年组、中年组及老年组,每组10只。体外Langendorff灌流心脏,右心室刺激。分别记录各组左心房肌在4 0 0ms刺激周长下动作电位复极到90 %、5 0 %及2 0 %时的单相动作电位时程(MAPD90 )、MAPD50 、MAPD2 0 和心房有效不应期,以及在不同刺激周长下的MAPD90 、MAPD50 、MAPD2 0 。结果　MAPD各时相和有效不应期都随着年龄的增加而出现延长(P <0 .0 1) ;但老年组缩短。在同一年龄组中,刺激频率增加使动作电位时程都相应缩短,以MAPD90 明显;中年组MAPD改变明显。结论　年龄是影响心脏电活动重要的独立因素之一。

Age-associated change of monophasic action potential of left atrial muscle in rat

Objective To study the effect of age on monophasic action potential (MAP) of atrial muscle. Methods According to their age, Wistar rats (n=40) were divided into 4 groups:young group, adult group, middle-aged group and old group.The MAP at 20%(MAPD_ 20),50%(MAPD_ 50) and 90%(MAPD_ 90) repolarization and effective refractory period (ERP) of left atrium at the same pacing cycle length (S_1S_1=400 ms), and the MAPD at other shorter pacing cycle length were assayed for each group.Result With age advancing, all phases of MAP and ERP were prolonged (P<0.01), while the MAPD and ERP of left atrial muscle in old group became short. In the same age group, the MAPD shortened with pacing frequency increasing.The change in middle-aged group was marked, and mainly appeared in MAPD_ 90.Conclution Age is an important factor influencing heart electrophysiology.