ESTRADIOL BINDING TO CELL-SURFACE RAISES CYTOSOLIC-FREE CALCIUM IN T-CELLS

The Fura-2 method is used to examine a possible action of 17 beta-estr adiol (E-2) on [Ca2+](i) of splenic T cells isolated from female C57BL /10 mice, E-2 concentrations between 10 fM and 10 nM induce a rapid an d dose-dependent increase in [Ca2+](i) due to Ca2+ influx and release of Ca2+ from intracellular stores, Ca2+ influx is mediated by Ca2+ cha nnels which are completely blockable by Ni2+ and partly by nifedipine, The antiestrogen tamoxifen does not inhibit the E-2-induced rise in [ Ca2+](i), Ca2+ influx and Ca2+ release from intracellular stores is al so inducible by plasma membrane impermeable E-2 conjugated to BSA, E-2 -BSA-FITC binds to the surface of T cells of both the CD4(+) and CD8() subset, Our data suggest a novel E-2-signalling pathway in T cells w hich is not mediated through the classical nuclear estrogen receptor r esponse but rather through putative plasma membrane receptors for E-2. (C) 1998 Federation of European Biochemical Societies.