5-HYDROXYTRYPTAMINE-EVOKED [CA2-CELLS(](I) OSCILLATIONS IN RAT C6 GLIOMA)

We have investigated the modulation of the intracellular calcium conce ntration ([Ca2+](i)) in rat C6 glioma cells following their activation by the agonists 5-hydroxytryptamine . HCl (5-HT) and bradykinin, usin g single cell imaging of [Ca2+](i) with the calcium-sensitive dye Fura -2. The majority of the signals observed involved release of calcium f rom intracellular stores, and after prolonged application of 5-HT, but not bradykinin, the cells exhibited oscillations in [Ca2+](i) levels. These calcium oscillations were dependent on the presence of extracel lular calcium, and were unaffected by the calcium channel antagonists nifedipine and verapamil. Caffeine, which in other cell types is able to release calcium from inositol trisphosphate-insensitive stores, had very little effect on [Ca2+](i) levels in C6 cells. On the other hand , bradykinin, although able to elevate [Ca2+](i) probably by acting vi a the B-2-receptor subtype, was unable to induce any calcium oscillati ons in these cells. Copyright (C) 1996 Elsevier Science Ltd.