大鼠心房肌电生理特性的增龄性变化

目的探讨年龄对心房肌单相动作电位(MAP)和有效不应期(ERP)的影响,及其与心房颤动(房颤)的关系。方法选取Wistar大鼠40只分为青年组、成年组、中年组和老年组4组。Langendorff体外灌流心脏。分别测量各组心房肌在400ms刺激周长下MAP复极到90%、50%及20%时的时程(MAPD90、MAPD50、MAPD20)和ERP,以及其他不同刺激周长下的MAPD。结果在400ms刺激周长下,4组大鼠右心房肌MAPD90随年龄增长而逐渐延长〔(75±5)(、123±8)(、140±11)和(140±14)ms,均为P<0.01〕;而左心房肌青年组至中年组延长分别为〔(60±4),(120±3),(139±7)〕,老年组缩短〔(102±14)ms,均为P<0.01〕。心房肌ERP的增龄性变化规律与MAPD90相同。刺激周长从400ms缩短到250ms,右心房肌MAPD90缩短程度从青年组到老年组逐渐增加;左心房肌以老年组缩短程度最小。结论左右心房肌电生理特性增龄性变化规律不同。老年期心房电生理变化可能有利于房颤的发生。

Age-associated electrophysiological changes of rat atrial muscle

Objective To investigate the age-associated changes of electrophysiological properties of atrial muscle and the relationship between these changes and atrial fibrillation (AF). Methods According to their ages forty Wistar rats were divided into 4 age groups: young group, adult group, middle-aged group and old group (n=10 each group ). Hearts were isolated and perfused by Langendorff. MAP (monophasic action potential) of atrial muscle was recorded. MAPD (duration of MAP) and ERP (effective refractory period) at 400 ms of the stimulation cycle length, and MAPD at other different stimulation cycle lengths were measured in each group. Results At the stimulation cycle length of 400 ms, MAPD_(90) of right atrial muscle prolonged gradually from young group to old group (P<0.01). MAPD_(90) of left atrial muscle prolonged from young group to middle-aged group, while it was shorter in old group than that in middle-aged group(P<0.01). ERP of atrial muscle showed the same change trends as MAPD_(90). At the same change of stimulation cycle length (from 400 ms to 250 ms), with age advancing the shortening extent of MAPD_(90) of right atrial muscle increased gradually, and that of left atrial muscle was the least in old group. Conclusions The age-associated change trends of eletrophysiological properties in left and right atrial muscle are not identical. The eletrophysiological properties of atrial muscle in old group might make atrial fibrilatim easily happen.