To clarify the effect of extracellular ATP in cultured C6 glioma cells, ATP-induced cytosolic free calcium ((Ca2+)i) mobilization and cell proliferation were investigated. ATP-induced (Ca2+)i increased in a dose-dependent manner (10-7 M apprx 10-3 M). ATP-induced (Ca2+)i increases were slightly slowed in extracellular calcium-free conditions especially in sustained phase. ATP-induced (Ca2+)i increment was also inhibited by the pretreatment of U73122, a phospholipase C (PLC) inhibitor, in a time-dependent manner. Suramin, a putative P2Y receptor antagonist, dose-dependently weakened ATP-induced (Ca2+)i mobilization. Significant increases in cell proliferation were observed at 2, 3, and 4 days after ATP was added. Stimulated cell proliferation was also observed with adenosine at days 2 and 3. This cell proliferation was significantly inhibited by the treatment with suramin. Ionomycin also stimulated cell proliferation in a concentration-dependent manner. In conclusion, we suggest that extracellular ATP stimulates C6 glioma cell proliferation via intracellular free calcium mobilization mediated by purinoceptor.
Adenosine ; Adenosine Triphosphate* ; Calcium* ; Cell Proliferation* ; Cytosol ; Glioma* ; Ionomycin ; Receptors, Purinergic ; Suramin ; Type C Phospholipases