钠和钾对人红细胞钙泵的调节作用。

The modulation of the calcium pump of human red cells by Na+ and K+.

作者信息

Romero P J, Romero E

出版信息

Biochim Biophys Acta. 1984 Dec 5;778(2):245-52. doi: 10.1016/0005-2736(84)90365-1.

Abstract

The sidedness of Ca2+-pump activation by Na+ and K+ was studied by atomic absorption spectrophotometry in human erythrocyte ghosts, which had been prepared in dextran solutions and resealed to alkali cations. When ghosts were incubated in an all-choline medium, the increase in Na+i elicited an inhibitory-stimulatory effect on Ca2+ extrusion. By contrast, only a stimulatory action was induced when choline was replaced by Na+o. A dual effect on active Ca2+ efflux was also produced by increasing K+i or K+o. The biphasic response to the latter, however, was absent from high-K+ ghosts. Furthermore, the stimulation obtained at high K+o was additive to that elicited by K+i. The results suggest that Na+ and K+ stimulate the Ca2+ pump of human red cells through two different mechanisms. The first one appears to be an electric coupling between Ca2+ efflux and the external activating cation. The other seems associated with the molecular reactions of the Ca2+-pump protein.

摘要

通过原子吸收分光光度法，在葡聚糖溶液中制备并重新封闭碱金属阳离子的人红细胞血影中，研究了Na⁺和K⁺对Ca²⁺泵激活的方向性。当血影在全胆碱培养基中孵育时，细胞内Na⁺增加对Ca²⁺外流产生抑制-刺激作用。相比之下，当胆碱被细胞外Na⁺取代时，仅产生刺激作用。增加细胞内K⁺或细胞外K⁺也对Ca²⁺的主动外流产生双重作用。然而，高K⁺血影对后者没有双相反应。此外，在高细胞外K⁺时获得的刺激与细胞内K⁺引起的刺激相加。结果表明，Na⁺和K⁺通过两种不同机制刺激人红细胞的Ca²⁺泵。第一种似乎是Ca²⁺外流与外部激活阳离子之间的电偶联。另一种似乎与Ca²⁺泵蛋白的分子反应有关。