Wickenden A D, Jegla T J, Kaprielian R, Backx P H
Department of Medicine, Centre for Cardiovascular Research, and the Toronto Hospital, University of Toronto, Toronto, Canada M5G 2C4.
Am J Physiol. 1999 May;276(5):H1599-607. doi: 10.1152/ajpheart.1999.276.5.H1599.
The aim of the present study was to assess differences in transient outward potassium current (Ito) between the right ventricular free wall and the interventricular septum of the adult rat ventricle and to evaluate the relative contributions of Kv4.2, Kv4.3, and Kv1.4 to Ito in these regions. The results show that Ito is composed of both rapidly and slowly recovering components in the right wall and septum. The fast component had a significantly higher density in the right free wall than in the septum, whereas the slow component did not differ between the two sites. Kv4.2 mRNA and protein levels were also highest in the right wall and correlated with Ito density, whereas Kv4.3 was expressed uniformly in these regions. The kinetics of the rapidly recovering component of Ito in myocytes was similar to that recorded in tsa-201 cells expressing Kv4.2 and Kv4.3 channels. Kv1.4 mRNA and protein expression correlated well with the density of the slowly recovering Ito, whereas the recovery kinetics of the slow component were identical to Kv1.4 expressed in tsa-201 cells. In conclusion, expression of Kv1.4, Kv4.2, and Kv4.3 differs between regions in rat hearts. Regionally specific differences in the genetic composition of Ito can account for the region-specific properties of this current.
本研究的目的是评估成年大鼠心室右心室游离壁与室间隔之间瞬时外向钾电流（Ito）的差异，并评估Kv4.2、Kv4.3和Kv1.4对这些区域Ito的相对贡献。结果表明，Ito在右心室壁和室间隔中均由快速和缓慢恢复成分组成。快速成分在右心室游离壁中的密度显著高于室间隔，而缓慢成分在两个部位之间无差异。Kv4.2的mRNA和蛋白水平在右心室壁中也最高，且与Ito密度相关，而Kv4.3在这些区域中表达均匀。心肌细胞中Ito快速恢复成分的动力学与在表达Kv4.2和Kv4.3通道的tsa-201细胞中记录的相似。Kv1.4的mRNA和蛋白表达与缓慢恢复的Ito密度密切相关，而缓慢成分的恢复动力学与tsa-201细胞中表达的Kv1.4相同。总之，大鼠心脏不同区域之间Kv1.4、Kv4.2和Kv4.3的表达存在差异。Ito基因组成的区域特异性差异可解释该电流的区域特异性特性。
