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 receptor 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 microsomal Ca(2+)-ATPase inhibitor. Pretreatment with pertussis toxin did not affect the peak and sustained elevation of [Ca2+]i evoked by TG. Sodium nitroprusside and 8-bromo cyclic GMP did not affect an elevation of [Ca2+]i induced by TG. Phorbol 12-myristate 13-acetate, an activator of protein kinase C (PKC), and staurosporine, an inhibitor of PKC, did not modify an increase in [Ca2+]i induced by TG. Okadaic acid, an inhibitor of phosphatase, did not affect an increase in [Ca2+]i evoked by TG. Pretreatment with colchicine and cytochalasin D, drugs disrupting cytoskeleton, had no effect on a rise of [Ca2+]i induced by TG. Genistein and erbastatin analog, inhibitors of tyrosine kinase, inhibited an elevation of [Ca2+]i evoked by TG in a dose-dependent manner. The present results suggest that tyrosine kinase regulates capacitative Ca2+ entry into rat glioma C6 cells.