摘要
目的进一步了解心室跨壁电生理异质性的细胞学机制。方法以酶解法分离兔左心室心外膜(Epi)、中层(M)和心内膜层(Endo)心肌细胞,应用膜片钳技术研究左心室钠电流(INa)和瞬间外向钾电流(Ito)的跨壁异质性。结果①三层细胞的INa均呈电压依赖性,当电压相同时M细胞的电流密度较大;M细胞的INa失活最快,与Epi、Endo相比P<0.05;三层细胞的INa灭活后再恢复曲线无明显差异。②三层细胞的Ito均呈电压依赖性激活过程,当电压相同时Epi细胞的电流密度较大;Epi的失活较快,M细胞的Ito灭活后再恢复未见明显变化。结论兔左室游离壁三层心肌细胞INa和Ito的分布及动力学特性存在异质性,这可能是动作电位形态差异及折返性心律失常发生的离子基础。
[WT10.HZ] Objective To study the heterogeneities transmural of sodium (I_ Na) current and trsansient outward current (I_ to) among epicardial(Epi), midmyocardial (M) and endocardial (Endo) myocytes from rabbit left ventricle. Methods Myocytes were dissociated enzymatically, I_ Na and I_ to were recorded using whole-cell patch clamp techniques. Heterogeneities transmural of I_ Na and I_ to was compared. [WT10.HZ]Results ①I_ Na current density of the three subtypes of myocytes were volta-dependent. M had the largest I_ Na density and Epi the smallest at the same test potential. M cells inactivated faster than the other two types. There were no significant differences in the I_ Na recovery curves from inactivation among the three subtypes of myocytes. ②I_ to density of the three subtypes of myocytes were voltage-dependent. Epi had the largest while Endo had smallest I_ to density. The I_ to density in Epi cells was larger than in M and Endo. I_ to inactivated faster in Epi cells than in the other two subtypes, and there was no significant difference among the three subtypes of myocytes in recovery courses. The heterogeneities of transmural I_ Na and I_ to may be the ionic bases of differences in morphology of action potentials among three subtypes of myocytes and reentant arrhythmias.
出处
《基础医学与临床》
CSCD
北大核心
2005年第6期556-560,共5页
Basic and Clinical Medicine
