CA2+-DEPENDENT K+ CHANNEL ACTIVITY IN RAT GLIOMA-CELLS INDUCED BY BRADYKININ STIMULATION AND BY INOSITOL 1,4,5-TRISPHOSPHATE INJECTION

1. A glial cell line derived from C6 rat glioma eels has been shown previously to respond to extracellular pulses of bradykinin or intracellular injection of inositol 1,4,5-trisphosphate (Ins-P-3) with a slow hyperpolarizing response due to activation of a K+ current (G. Reiser ef al., Brain Res. 506, 205-214; 1990). 2. We determined the ensuing single-channel activity, which is most likely caused by Ca2+ released from internal stores after bradykinin stimulation. Bradykinin-activated channels were selectively permeable to K+, but not to Na+ or to Cl-, and exhibited conductances of mainly 40 and 50 pS. In glioma cells the same type of channel was activated by intracellular injection of Ins-P-3 and by extracellular bradykinin pulses.