Inositol 1,4,5-Trisphosphate and Basal Ca2+Release Is Affected by the Cytoplasmic Concentration of Cl−in Endothelial Cells

Abstract

The effects of varying Cl−concentration in the intracellular bathing medium, on IP3-induced45Ca2+release from internal stores, were examined in saponin-permeabilised bovine aortic endothelial (BAE) cells. Results from this study show that the release of Ca2+from the internal stores is affected by the cytoplamic concentration of Cl−ions. Complete replacement of Cl−with gluconate augmented IP3(3 μM)-induced45Ca2+release by 33 ± 8%. Replacement of both Cl−and K+with gluconate and NMG, respectively, had no significant effect on45Ca2+release. However, resting levels of internal45Ca2+were found to be affected by Cl−removal. These data suggest that in BAE cells, IP3and also basal45Ca2+release may be regulated by the physiological intracellular Cl−concentration.