Glitsch H G
Arbeitsgruppe Muskelphysiologie, Fakultät für Biologie, Ruhr-Universität Bochum, Bochum, Germany.
Physiol Rev. 2001 Oct;81(4):1791-826. doi: 10.1152/physrev.2001.81.4.1791.
Like several other ion transporters, the Na(+)-K(+) pump of animal cells is electrogenic. The pump generates the pump current I(p). Under physiological conditions, I(p) is an outward current. It can be measured by electrophysiological methods. These methods permit the study of characteristics of the Na(+)-K(+) pump in its physiological environment, i.e., in the cell membrane. The cell membrane, across which a potential gradient exists, separates the cytosol and extracellular medium, which have distinctly different ionic compositions. The introduction of the patch-clamp techniques and the enzymatic isolation of cells have facilitated the investigation of I(p) in single cardiac myocytes. This review summarizes and discusses the results obtained from I(p) measurements in isolated cardiac cells. These results offer new exciting insights into the voltage and ionic dependence of the Na(+)-K(+) pump activity, its effect on membrane potential, and its modulation by hormones, transmitters, and drugs. They are fundamental for our current understanding of Na(+)-K(+) pumping in electrically excitable cells.
与其他几种离子转运体一样，动物细胞的钠钾泵是生电的。该泵产生泵电流I(p)。在生理条件下，I(p)是外向电流。它可以通过电生理方法进行测量。这些方法能够在钠钾泵的生理环境，即细胞膜中，研究其特性。细胞膜分隔了细胞质和细胞外介质，二者具有明显不同的离子组成，且细胞膜上存在电位梯度。膜片钳技术的引入和细胞的酶法分离促进了对单个心肌细胞中I(p)的研究。本综述总结并讨论了从分离的心肌细胞中测量I(p)所获得的结果。这些结果为钠钾泵活性的电压和离子依赖性、其对膜电位的影响以及激素、递质和药物对它的调节提供了新的、令人兴奋的见解。它们对于我们目前对可兴奋细胞中钠钾泵转运的理解至关重要。
