BRADYKININ POTENTIATES ACETYLCHOLINE-INDUCED RESPONSES IN NATIVE ENDOTHELIAL-CELLS FROM RABBIT AORTA

Membrane potential and intracellular [Ca2+] were measured in freshly isolated rabbit aortic endothelial cells. Acetylcholine (10 mu M) induced transient membrane hyperpolarization and increased [Ca2+](i). Bradykinin (4 mu M) had no direct effect on membrane potential or [Ca2+](i) on its own, but potentiated the subsequent ACh response. It changed the usual transient ACh response to a maintained hyperpolarization. The maintained hyperpolarization was blocked by NiCl2 and TEA, indicating an involvement of receptor-operated-Ca2+ channel and Ca2+-dependent K+-channel activity. This potentiating effect of bradykinin in isolated cells was confirmed in organ bath studies using isolated aortic rings. (C) 1995 Academic Press, Inc.