Na+/H+ exchange and Ca2+ influx

FEBS Letters

Akkerman, Jan Willem N.²  Siffert, Winfried¹ 

[1] Max-Planck-Institut für Biophysik, Kennedyallee 70, D-6000 Frankfurt am Main 70, FRG;Department of Haematology, University Hospital, 3511 GVUtrecht, The Netherlands

关键词: Platelet;    Endothelial cell;    Lymphocyte;    Smooth muscle cell;    Na+/H+ exchange;    [Ca2+]i;    cytosolic free Ca2+ concentration;    Ca2+ 0;    extracellular Ca2+;    EIPA;    ethylisopropylamiloride;    [H+]i;    cytosolic H+ concentration;    [Na+]i;    cytosolic Na+ concentration;    Na+ 0 extracellular Na+;    pHi;    cytosolic pH;    pH0;    extracellular pH;    Ins 1;    4;    5P3;    inositol 1;    4;    5 trisphosphate;   

DOI  :  10.1016/0014-5793(89)81480-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Cell stimulation raises the cytosolic free Ca²⁺ concentration, [Ca²⁺]_i, and induces activation of Na⁺/H⁺ exchange which raises the cytosolic pH, pH_j. Recent studies have addressed the question whether Na⁺/H⁺ exchange plays a role in Ca²⁺ influx and, specifically, whether a rise in pH_i alone suffices to open Ca²⁺ channels in the plasma membrane. Artificial cytosolic alkalinization can induce Ca²⁺ uptake across the plasma membrane of endothelial cells, lymphocytes and smooth muscle cells. Furthermore, inhibition of Na⁺/H⁺ exchange reduces aganist-induced Ca²⁺ influx in endothelial cells and platelets which supports the concept that pH_i may regulate the opening of Ca²⁺ channels in the plasma membrane. Although these findings argue in favour of a role of Na⁺/H⁺ exchange in Ca²⁺ influx, the onset of pH_i and Ca²⁺ rises, measured with fluorescent indicators, suggests that the increase in [Ca²⁺]_i distinctly precedes the increase in pH_i. This challenges the concept that alkalinization per se is a sufficient signal for the opening of Ca²⁺ channels in the plasma membrane.

【 授权许可】

Unknown