Nicotinic receptor-mediated intracellular calcium release in cultured bovine adrenal chromaffin cells

Abstract When cultured bovine adrenal chromaffin cells were stimulated by a nicotinic agonist, carbamylcholine (0.3 mM) or 1,1-dimethyl-4-phenylpiperazinium (50 μM), in the Ca 2+ -free medium containing 0.1 mM ethyleneglycoltetraacetic acid, intracellular free Ca 2+ concentration ([Ca 2+ ] i ) rose from approximately 90 to 140 nM. High K + (56 mM) and veratridine (50 μM) had no effect on the [Ca 2+ ] i in Ca 2+ -free medium. The carbamylcholine-evoked rise in [Ca 2+ ] i was blocked by hexamethonium (0.1 mM) but not by atropine (1 μM). Furthermore, the carbamylcholine-evoked rise in [Ca 2+ ] i was inhibited by an intracellular Ca 2+ antagonist, 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxy-benzoate hydrochloride (10 μM) but not by a calmodulin antagonist, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (20 μM). These results show the existence of intracellular Ca 2+ store sites, from which Ca 2+ is released upon nicotinic receptor stimulation, in cultured adrenal chromaffin cells.