Capacitative Ca2+ entry involves Ca2+ influx factor in rat glioma C6 cells

Capacitative Ca2+ entry exists in rat glioma C6 cells; however, how the inf ormation of depletion of Ca2+ in intracellular stores transmits to the plas ma membrane is unknown. In the present study, we examined whether Ca2+ infl ux factor (CIF) causes capacitative Ca2+ entry in C6 cells. CIF was extract ed from non-treated (Non-CIF), bombesin-treated (BBS-CIF) and thapsigargin- treated (TG-CIF) C6 cells by a reverse-phase silica cartridge. The addition of BBS-CIF and TG-CIF gradually increased cytoplasmic Ca2+ concentration ( [Ca2+](i)) but Non-CIF did not increase [Ca2+],. Neither BBS-CIF nor TG-CIF elevated [Ca2+](i) in the absence of extracellular Ca2+. Gd3+ inhibited th e increase in [Ca2+](i) induced by BE S-CIF and TG-CIF. Genistein abolished an elevation of [Ca2+](i) induced by BBS-CIF and TG-CIF. BBS-CIF and TG-CI F did not increase inositol 1,4,5-trisphosphate accumulation. The results s uggest that capacitative Ca2+ entry is caused by CIF in rat glioma C6 cells .