索它洛尔对豚鼠心室肌复极不均一性影响的实验研究

Effect of sotalol on repolarization heterogenity in guinea pig left ventricle

目的 :探讨豚鼠左室游离壁不同区域的电生理异质性及其对索它洛尔的反应。方法 :用标准玻璃微电极技术观察索它洛尔使用前后不同刺激频率时豚鼠左室游离壁不同区域动作电位 (AP)的变化。结果 :心内膜心肌细胞的动作电位时程 (APD)较心肌中层及心外膜细胞长 (P <0 .0 0 1)。心内膜、心肌中层及心外膜细胞的AP复极到 90 %的APD(APD90 )在刺激频率为 0 .2Hz时分别是 ( 2 33± 3)、( 2 16± 2 )及 ( 2 10± 3)ms ,在刺激频率为 3.3Hz时分别是 ( 172± 4)、( 163± 3)及 ( 15 6± 3)ms ,心内膜心肌细胞具有明显的慢频率依赖性。用索它洛尔后各层细胞APD等程度延长 ,各层的APD仍有明显差异 (P <0 .0 0 1)。结论 :豚鼠左室游离壁各层心肌细胞的APD存在明显的跨壁梯度 ,心内膜的细胞有更长的APD和更明显的慢频率依赖性 ;索它洛尔可等程度地延长各层心肌细胞的APD 。

Objective To test electrophysiological heterogenity and different response to class Ⅲ agents of different regions in the guinea pig left ventricle.Method The study used a dermatome to obtain thin strips of free wall of left ventricle in guinea pig and standard microeletrode techniques to record transmembrane activity.Results Action potential duration measured at 90% repolarization (APD 90) was significantly longer in sub-endocardium cells than in mid-myocardium or sub-epicardium cells at all basic cycle lengths (BCLs) tested.At a BCL of 0.2Hz,APD 90 was (233±3),(216±2) and (210±3)ms in sub-endocardium,mid-myocardium,and sub-epicardium respectively;while at a BCL of 3.3Hz,it was (172±4),( 163±3) and (156±3)ms respectively.Thus APD-rate relations was more pronounced in the sub-endocardium.Sotalol-induced prolongated APD 90 was similar in the three regions studied.Conclusions There are significant transmural gradients in the electrophysiological properties of sub-epicardium,mid-myocardium, and sub-epicardium from the free wall of guinea pig left ventricle.Sub-endocardial myocytes have a longer APD 90 and the pronounced rate dependence in contrast to mid-myocardium and sub-epicardiac myocytes sotalol can not reduce transmural gradients.