过表达肌浆网钙ATP酶2a的转基因大鼠心肌细胞中增强的L型钙电流。

Enhanced L-type calcium currents in cardiomyocytes from transgenic rats overexpressing SERCA2a.

作者信息

Kamkin Andre, Kiseleva Irina, Theres Heinz, Eulert-Grehn Jaime-Jürgen, Wagner Kay-Dietrich, Scholz Holger, Vetter Roland

机构信息

Institut für Vegetative Physiologie;

出版信息

Exp Clin Cardiol. 2010 Winter;15(4):e109-15.

PMID:21264068

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC3016070/

Abstract

BACKGROUND

Previous research reported that transgenic rats overexpressing the sarco(endo)plasmic reticulum Ca(2+)-ATPase SERCA2a exhibit improved contractile function of the myocardium. Furthermore, impaired Ca(2+) uptake and reduced relaxation rates in rats with diabetic cardiomyopathy were partially rescued by transgenic expression of SERCA2a in the heart.

OBJECTIVE

To explore whether enhanced Ca(2+) cycling in the cardiomyocytes of SERCA2a transgenic rats is associated with changes in L-type Ca(2+) (I(Ca-L)) currents.

METHODS

The patch-clamp technique was used to measure whole-cell currents in cardiomyocytes from transgenic rats overexpressing SERCA2a and from wild-type (nontransgenic) animals.

RESULTS

The amplitudes of I(Ca-L) currents at depolarizing pulses ranging from -45 mV to 0 mV (350 ms duration, 1 Hz) were significantly higher in cardiomyocytes of SERCA2a transgenic rats than in nontransgenic rats (1985±48 pA [n=32] versus 1612±55 pA [n=28], respectively). The inactivation kinetics of I(Ca-L) showed subtle differences with increased tau fast and tau slow decay constants in cardiomyocytes of SERCA2a transgenic animals. Beta-adrenergic stimulation with 50 nM isoproterenol reduced tau fast and tau slow decay constants in cardiomyocytes of transgenic rats to values that were not significantly different from those in normal cardiomyocytes. Furthermore, isoproterenol enhanced I(Ca-L) currents 3.2-fold and 2.3-fold in cardiomyocytes with and without the SERCA2a transgene, respectively, and this effect was abolished by buffering intracellular Ca(2+) with BAPTA.

CONCLUSIONS

These findings indicate that enhanced Ca(2+) cycling in the hearts of SERCA2a transgenic rats, both under normal conditions and during beta-adrenergic stimulation, involves changes in I(Ca-L) currents. Modified I(Ca-L) kinetics may contribute, to some extent, to the improved contractile function of the myocardium of transgenic rats.

摘要

背景

先前的研究报道，过度表达肌浆网Ca(2+) - ATP酶SERCA2a的转基因大鼠心肌收缩功能得到改善。此外，糖尿病性心肌病大鼠心脏中Ca(2+)摄取受损和舒张速率降低通过心脏中转基因表达SERCA2a得到部分挽救。

目的

探讨SERCA2a转基因大鼠心肌细胞中增强的Ca(2+)循环是否与L型Ca(2+)（I(Ca-L)）电流变化有关。

方法

采用膜片钳技术测量过度表达SERCA2a的转基因大鼠和野生型（非转基因）动物心肌细胞中的全细胞电流。

结果

在 - 45 mV至0 mV（持续时间350 ms，1 Hz）的去极化脉冲下，SERCA2a转基因大鼠心肌细胞中I(Ca-L)电流幅度显著高于非转基因大鼠（分别为1985±48 pA [n = 32]和1612±55 pA [n = 28]）。I(Ca-L)的失活动力学显示出细微差异，SERCA2a转基因动物心肌细胞中快速和慢速衰减常数tau增加。用50 nM异丙肾上腺素进行β-肾上腺素能刺激可使转基因大鼠心肌细胞中的快速和慢速衰减常数tau降低至与正常心肌细胞无显著差异的值。此外，异丙肾上腺素分别使有和没有SERCA2a转基因的心肌细胞中的I(Ca-L)电流增强3.2倍和2.3倍，并且通过用BAPTA缓冲细胞内Ca(2+)消除了这种效应。