Functional Characterization of Inward Rectifier Potassium Ion Channel in Murine Fetal Ventricular Cardiomyocytes

[摘要] Aims Previous studies have shown the dramatic changes in electrical properties of murine fetal cardiomyocytes, while details on inward rectifier potassium current (IK1) are still seldom discussed. Thus we aimed to characterize the functional expression and functional role of IK1 in murine fetal ventricular cardiomyocytes. Methods Whole cell patch clamp was applied to investigate the electrophysiological properties of IK1. Quantitative real-time PCR, western blotting and double-label immunofluorescence were further utilized to find out the molecular basis of IK1. Results Compared to early developmental stage (EDS), IK1 at late developmental stage (LDS) displayed higher current density, stronger rectifier property and faster activation kinetics. It was paralleled with the downregulation of Kir2.3 and the upregulation of Kir2.1/Kir2.2. IK1 contributed to maintain the maximum diastolic potential (MDP), late repolarization phase (LRP) as well as the action potential duration (APD). However, the contribution to MDP and velocity of LRP did not change significantly with maturation. Conclusions During fetal development, the switch of IK1 subtypes from Kir2.1/Kir2.3 to Kir2.1 resulted in the dramatic changes in IK1 electrophysiological properties.

[学科分类] 分子生物学，细胞生物学和基因

[关键词] Excitability;Action potential;Cardiogenesis;Inward rectifier potassium current;Ventricular cardiomyocytes