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目的:研究家兔心肌肥厚时三层心肌细胞延迟整流钾电流慢激活成分异质性的改变及长期应用咪达普利(Imi)对此变化的作用。方法:缩窄兔单侧腹主动脉制备心肌肥厚模型,同时设Imi治疗组和假手术组,采用全细胞膜片箝技术记录兔心肌细胞动作电位和钾电流。结果:(1)肥厚心肌细胞的膜电容明显高于假手术组和Imi治疗组;其动作电位时程(APD)显著延长,尤其是中层细胞(M)延长最为显著;应用Imi后可逆转此延长效应;(2)肥厚心肌细胞上I_(ks,tail)密度均不同程度的降低,外膜和内膜细胞分别降低25.3％±2.9％和20.3％±4.7％,而M降低最为显著为38.0％±3.7％;用Imi后电流密度降低程度明显被缓解,该电流的跨室壁异质性减少。(3)在三层心肌细胞上I_(kr,tail)的差异不明显,且I_(kr,tail)密度在三组也改变较小。结论:长期应用Imi可以减少兔肥厚心肌细胞延迟整流钾电流慢激活成分的跨室壁异质性改变。
OBJECTIVE: To study the changes of the slow heterogeneity of delayed activation potassium current in three layers of myocardial hypertrophy in rabbits and the effect of long-term application of Imi on the changes. Methods: The model of myocardial hypertrophy was established by narrowing the unilateral abdominal aorta of rabbits. The Imi-treated group and the sham operation group were also established. Whole-cell patch-clamp technique was used to record the action potential and potassium current in rabbit cardiomyocytes. Results: (1) The membrane capacitance of hypertrophic cardiomyocytes was significantly higher than that of the sham operation group and the Imi treatment group. The duration of action potential duration (APD) was significantly prolonged, especially in the middle stage cells (M) (2) The density of I_ (ks, tail) in hypertrophic cardiomyocytes decreased to some extent, the outer membrane and intima decreased by 25.3% ± 2.9% and 20.3% ± 4.7%, respectively, while the M decreased the most significantly by 38.0% % ± 3.7%. The reduction in current density was significantly alleviated with Imi, and the cross-wall heterogeneity of the current decreased. (3) The difference of I_ (kr, tail) in three layers of myocardial cells was not obvious, and the density of I_ (kr, tail) also changed less in three groups. CONCLUSION: Long-term administration of Imi can reduce the transmural heterogeneity of slow-acting components of delayed rectifier potassium currents in hypertrophied cardiomyocytes.