通过原生和克隆的心脏Na+/Ca2+交换器进行Na+转移时的电荷运动
D W Hilgemann1, D A Nicoll, K D Philipson
1Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235.
Nature
|August 22, 1991
概括
心脏-交换器 (NCX) 在 (Na+) 运输过程中移动正电荷. 这项研究揭示了心肌细胞中Na+运动的电源性质,澄清了NCX反应周期.
科学领域:
- 生物物理学的生物物理.
- 心血管生理学心血管生理学
背景情况:
- 心脏-交换器 (NCX) 在调节心脏细胞内细胞内水平方面发挥着至关重要的作用.
- 电生成性和NCX的详细反应周期尚未完全理解,特别是离子运输的固态度.
研究的目的:
- 为了研究心脏NCX的Na+转位的电源性质.
- 通过将电荷运动与Na+运输联系起来,阐明NCX反应周期的细节.
主要方法:
- 利用来自心脏肌细胞和表达克隆心脏NCX的卵细胞的巨型膜贴片.
- 测量了Na(+) 诱导的电荷运动,以应对细胞质Na+度在没有Ca2+的情况下逐步增加的反应.
- 定量化的稳定状态Na+/Ca2+交换流 (INaCa) 密度和营业额.
主要成果:
- 由心脏NCX进行的Na+转位已被证明与正电荷运动有关.
- 估计大约400个每平方微米的交换器在几内亚猪肉和最大的周转率为5000s-1.
- 观察到明显的离子亲和度增加,对抗离子度降低,电压依赖性丧失,Ca2+度降低,支持电子中性Ca2+转位.
结论:
- 在NCX循环中,主要的电生成步骤似乎发生在Na+转位通路的细胞外末端.
- 这些发现提供了关于心脏NCX的反应机制和静脉测量学的见解.
- 这项研究阐明了心脏-交换器的电生理行为.
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