INVOLVEMENT OF TYROSINE KINASE IN CAPACITATIVE CA2+ ENTRY PATHWAY IN RAT GLIOMA C6 CELLS

Capacitative Ca2+ entry, a main pathway of Ca2+ entry evoked by recept or activation, is widely confirmed in various types of cells. However, the mechanism of the activation of capacitative Ca2+ entry is unknown . We checked the several candidates for the mechanism of capacitative Ca2+ entry pathway in rat glioma C6 cells using thapsigargin (TG), a m icrosomal Ca2+-ATPase inhibitor. Pretreatment with pertussis toxin did not affect the peak and sustained elevation of [Ca2+](i) evoked by TC T. Sodium nitroprusside and 8-bromo cyclic GMP did not affect an eleva tion of [Ca2+](i) induced by TG. Phorbol 12-myristate 13-acetate, an a ctivator of protein kinase C (PKC), and staurosporine, an inhibitor of PKC, did not modify an increase in [Ca2+](i) induced by TG. Okadaic a cid, an inhibitor of phosphatase, did not affect an increase in [Ca2+] (i) evoked by TG. Pretreatment with colchicine and cytochalasin D, dru gs disrupting cytoskeleton, had no effect on a rise of [Ca2+](i) induc ed by TG. Genistein and erbastatin analog, inhibitors of tyrosine kina se, inhibited an elevation of [Ca2+](i) evoked by TG in a dose-depende nt manner. The present results suggest that tyrosine kinase regulates capacitative Ca2+ entry into rat glioma C6 cells.