兔心肌细胞中钠钾泵电流-电压关系对细胞内钠、钾和铯的依赖性。

Dependence of Na+-K+ pump current-voltage relationship on intracellular Na+, K+, and Cs+ in rabbit cardiac myocytes.

作者信息

Hansen Peter S, Buhagiar Kerrie A, Kong Benjamin Y, Clarke Ronald J, Gray David F, Rasmussen Helge H

机构信息

Department of Cardiology, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia.

出版信息

Am J Physiol Cell Physiol. 2002 Nov;283(5):C1511-21. doi: 10.1152/ajpcell.01343.2000.

DOI:10.1152/ajpcell.01343.2000

PMID:12372812

Abstract

To examine effects of cytosolic Na+, K+, and Cs+ on the voltage dependence of the Na+-K+ pump, we measured Na+-K+ pump current (Ip) of ventricular myocytes voltage-clamped at potentials (Vm) from 100 to +60 mV. Superfusates were designed to eliminate voltage dependence at extracellular pump sites. The cytosolic compartment of myocytes was perfused with patch pipette solutions with a Na+ concentration ([Na]pip) of 80 mM and a K+ concentration from 0 to 80 mM or with solutions containing Na+ in concentrations from 0.1 to 100 mM and K+ in a concentration of either 0 or 80 mM. When [Na]pip was 80 mM, K+ in pipette solutions had a voltage-dependent inhibitory effect on Ip and induced a negative slope of the Ip-Vm relationship. Cs+ in pipette solutions had an effect on Ip qualitatively similar to that of K+. Increases in Ip with increases in [Na]pip were voltage dependent. The dielectric coefficient derived from [Na]pip-Ip relationships at the different test potentials was 0.15 when pipette solutions included 80 mM K+ and 0.06 when pipette solutions were K+ free.

摘要

为研究胞质中的Na⁺、K⁺和Cs⁺对Na⁺-K⁺泵电压依赖性的影响，我们测量了在100至 +60 mV电位（Vm）下电压钳制的心室肌细胞的Na⁺-K⁺泵电流（Ip）。设计灌流液以消除细胞外泵位点的电压依赖性。用Na⁺浓度（[Na]pip）为80 mM且K⁺浓度从0至80 mM的膜片钳溶液或用Na⁺浓度从0.1至100 mM且K⁺浓度为0或80 mM的溶液灌流心肌细胞的胞质部分。当[Na]pip为80 mM时，膜片钳溶液中的K⁺对Ip具有电压依赖性抑制作用，并导致Ip-Vm关系出现负斜率。膜片钳溶液中的Cs⁺对Ip的影响在性质上与K⁺相似。随着[Na]pip增加Ip的增加具有电压依赖性。当膜片钳溶液包含80 mM K⁺时，在不同测试电位下从[Na]pip-Ip关系得出的介电系数为0.15，而当膜片钳溶液不含K⁺时为0.06。