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目的研究表明犬心室壁中层心肌细胞(M细胞)具有独特的电生理特征,如动作电位时程有较强的频率依赖性。本文观察M细胞瞬时外向钾电流传性,并讨论其与动作电位特征的关系。方法酶解犬左心室心肌M细胞及心内、外膜层肌细胞,应用膜片钳全细胞记录技术观察并比较其单个心肌细胞的瞬时外向钾流传性。结果(1)M细胞和心外膜层肌细胞的瞬时外向钾流较心内膜层肌细胞明显地大。(2)M细胞瞬时外向钾流具有显著频率依赖性,即基础刺激周长长时其强度明显增加。结论 M细胞具有较大的瞬时外向钾电流是其显著“峰和园顶”形态和动作电位时程较强的频率依赖性的离子基础之一。
AIM: To investigate the unique electrophysiological characteristics of middle myocardial cells (M cells) in canine ventricular wall, such as the action potential duration has a strong frequency dependence. In this paper, M cell transient outward potassium current transfer, and discuss the relationship with the characteristics of the action potential. Methods Enzyme-linked immunosorbent assay was used to observe the transient outward potassium transport of single myocytes in M cells of cardiac canine and myocardial cells of epicardial and adventitial layers. Results (1) The transient outward potassium currents in M cells and epicardial myocytes were significantly larger than those in the endocardial layer. (2) M cell transient outward potassium flow has a significant frequency dependence, that is, when the base stimulus perimeter long, its intensity increased significantly. Conclusion M cells with larger transient outward potassium currents are one of the ion bases of their significant “peak and dome” morphology and the strong frequency-dependent ionization of action potentials.