兔左室三层心肌细胞非特异性阳离子电流的特性

目的研究兔左室除钾电流外是否还存在其它复极外向电流,并进一步研究其在三层心肌细胞上的分布。方法采用胶原酶二步消化法分离兔心肌细胞,用锐利眼科剪分离左室游离壁内、中、外三层心肌,改变灌流液的成份,采用全细胞膜片钳记录离子电流。结果在兔左室肌细胞记录到一种新的电压依赖性、非特异性阳离子电流。该离子通道对Na+、K+、Li+、Cs+通透,对Cl-不通透,能够被Gd3+和La3+阻断。该通道在三层心肌细胞的密度分布不同,中层心肌细胞的电流密度明显小于内层和外层心肌细胞。结论非特异性阳离子电流参与了兔左室心肌细胞的电生理异质性的形成。

The characteristics of nonselective cation current in rabbit left ventricular three layers myocytes.

Objective To investigate if there is any other outward currents except for ITo and Ik in rabbit three-layer left ventricular(LV) cardiomyocytes and its contribution.Methods Myocytes were isolated by enzymatic method.The sub-endocardial(Endo) and sub-epicardial (Epi) tissues were separated from the mid-layer region(midmyocardium,M) with opthalmic scissors.Single cells in each region were obtained by gentle shaking and dispersing in a chamber filled with normal Tyrode′s solution.The whole-cell patch clamp technique was used to record the current while change the composition of the perfusate.Results A new voltage-dependent current,nonselective cation current(INSCC) was recorded in rabbit LV wall.Na+,K+,Li+,Cs+ could permeate through the INSCC channel while Cl-could not permeate through it.And it could be blocked by Gd3+ and La3+.INSCC was observed in rabbit LV wall and the current density of midmyocardial myocytes was smaller than that of epicardial and endocardial myocytes.Conclusion INSCC contributs to the electrophysiological heterogeneity of rabbit LV wall.