豚鼠左心室中层肌细胞电生理特征的实验研究

目的　观察 2 5 0～ 80 0g豚鼠左心室游离壁内、外膜层及中层肌细胞的复极不均一性及室壁中层是否具有Mcell的特性。方法　应用标准玻璃微电极技术 ,记录不同基础周长时豚鼠左心室游离壁内、外膜层及中层肌细胞跨膜动作电位各种参数变化。结果　在所有刺激周期(BCL)测试中 ,中层肌细胞的复极至动作电位 90 %的时程 (APD90 )较心内、外膜层肌细胞长 ,在BCL =3 0 0ms时 ,内、外膜层及中层肌细胞的APD90 分别为 (2 0 7± 1 5 )ms,(2 1 4± 2 1 )ms,(2 1 5±2 7)ms( x±s;n =9;体质量 2 5 0～ 3 5 0 g)及 (2 0 6± 3 4 )ms,(1 99± 2 8)ms,(2 4 7± 2 5 )ms( x±s;n=1 0 ;体质量 3 5 0～ 80 0 g)。在BCL =3 0 0 0ms时 ,内、外膜层及中层肌细胞的APD90 分别为 (2 94± 3 4 )ms,(2 90± 49)ms,(3 1 3± 5 0 )ms( x±s;n =1 0 ;体质量 2 5 0～ 3 5 0 g)及 (2 96± 42 )ms,(2 5 9± 5 8)ms,(3 2 8± 3 6 )ms( x±s;n =1 0 ;体质量 3 5 0～ 80 0 g)。中层肌细胞APD 频率依赖性较心内、外膜层肌细胞更明显。结论　豚鼠左心室游离壁存在复极不均一性 ,中层肌细胞有更长的APDs,更明显的APD 频率依赖性。豚鼠左心室游离壁中层细胞具有Mcell的电生理特性。

The study of electrophysiologic features of cells in the mid-myocardium layers of the guinea pig

Objective To identify repolarization heterogenity and M cells in guinea pig left free ventricular. Methods A dermatome was used to obtain thin transmural strips of left free ventricular from the hearts of guinea pig(weight 250～800?g) and standard microeletrode techniques to record transmembrane action potential(TAP).Results Action potential duration at 90% repolarization(APD 90 ) was longer in mid-myocardial(MID) cells than in epicardium (EPI) and endocardium(ENDO) cells at all basic cycle lengths(BCL) tested.At a BCL of 300?ms,APD 90 was (207±15)ms,(215±27)?ms,(214±21)?ms in ENDO,MID and EPI cells ( ±s ; n =9;weight 250～350?g) and (206±34)?ms,(247±25)?ms,(199±4728)?ms( ±s ; n =10;weight 350～800?g).At a BCL of 3?000?ms,APD 90 was (294±34)?ms,(313±50)?ms,(290±49)?ms( ±s ; n =10;weight 250～350?g) in ENDO,MID and EPI cells and (296±42)?ms,(328±36)?ms,(259±58)?ms( ±s ; n =12;weight 350～800?g).APD-rate relations were more pronounced in the MID cells.Conclusions There is the existence of important transmural electrical heterogenity in guinea pig ventricular myocardium,and provides datd in support of the M cells in the mid-myocardial layers of the guinea pig ventricular exhibiting longer APDs and more important APD-rate relations.