Muscarinic receptor-mediated catecholamine secretion from isolated guinea pig adrenal chromaffin cells
Misbahuddin, M.
Tokushima Journal of Experimental Medicine 34(3-4): 101-105
1987
ISSN/ISBN: 0040-8875 PMID: 3503381 Document Number: 287392
Adrenal chromaffin cells were isolated by collagenase digestion of guinea pig adrenal medulla and the effects of muscarine on their Ca2+ movements of catecholamine (CA) secretion were examined. Their secretion of CA was stimulated by acetylcholine (ACh), muscarine, methacholine and pilocarpine. Muscrine was a more potent secretagogue than nicotine. Muscarine-induced CA secretion was slow in onset and was dependent on the presence of extracellular Ca2+. Muscarine did not cause significant uptake of 45Ca2+ by the cells, but experiments using the fluorescent Ca2+ indicator quin 2 showed that it caused increase intracellular free Ca2+, [Ca2+]i, which was sufficient to stimulate CA secretion. The intracellular Ca2+ antagonist 8-(N,N-diethylamino) octyl-3,4,5-trimethoxybenzoate (TMB-8) inhibited both the CA secretion and the increase in [Ca2+]i induced by muscarine. These results indicate that muscarine stimulates CA secretion by mobilizing Ca2+ from intracellular stores.