Na + /H + exchange and Ca 2+ influx
1989; Wiley; Volume: 259; Issue: 1 Linguagem: Inglês
10.1016/0014-5793(89)81480-2
ISSN1873-3468
AutoresWinfried Siffert, Jan Willem N. Akkerman,
Tópico(s)Ion Channels and Receptors
ResumoCell stimulation raises the cytosolic free Ca 2+ concentration, [Ca 2+ ] 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 Ca 2+ influx and, specifically, whether a rise in pH i alone suffices to open Ca 2+ channels in the plasma membrane. Artificial cytosolic alkalinization can induce Ca 2+ uptake across the plasma membrane of endothelial cells, lymphocytes and smooth muscle cells. Furthermore, inhibition of Na + /H + exchange reduces aganist‐induced Ca 2+ influx in endothelial cells and platelets which supports the concept that pH i may regulate the opening of Ca 2+ channels in the plasma membrane. Although these findings argue in favour of a role of Na + /H + exchange in Ca 2+ influx, the onset of pH i and Ca 2+ rises, measured with fluorescent indicators, suggests that the increase in [Ca 2+ ] i distinctly precedes the increase in pH i . This challenges the concept that alkalinization per se is a sufficient signal for the opening of Ca 2+ channels in the plasma membrane.
Referência(s)