Effect of endothelin on Ca2+ influx, intracellular free Ca2+ levels and ligand binding to N and L type Ca2+ channels in rat brain

Abstract

The actions of endothelin, an endogenous vasoconstrictor compound with potent effects on various parameters of Ca2+ metabolism in peripheral tissue, were studied in several neuronal preparations. Endothelin, by itself, did not alter resting intracellular free Ca2+ levels or Ca2+ influx in either rat or chicken brain preparations; nor did it affect depolarization (K+) induced changes in these parameters. Endothelin also had no effect on the binding of [3H]-nitrendipine or [125I]-omega-conotoxin to "L " or "N" type channels respectively nor did it induce the release of endogenous acetylcholine from brain slices. The results show that, despite the proposed role of endothelin on voltage sensitive Ca2+ channels in peripheral tissue and despite the existence of endothelin binding sites on both smooth muscle and neurons, endothelin has no measurable effects on Ca2+ metabolism in neural tissue of central origin.