Effects of nicotinic and muscarinic stimulation on calcium flux and catecholamine release in isolated bovine adrenal medullary cells
Isosaki, M.
Tokushima Journal of Experimental Medicine 29(3-4): 155-161
1982
ISSN/ISBN: 0040-8875 PMID: 7170718 Document Number: 195300
Bovine adrenal medullary cells were isolated by sequential digestion of adrenal medullary slices with collagenase. The effects of nicotinic and muscarinic stimulations of these isolated cells on 45Ca2+ flux and release of catecholamine (CA) were examined. The isolated cells were incubated at 37.degree. C. Addition of acetylcholine (ACh) resulted in a rapid burst of CA release with increased uptake of 45Ca2+ by the cells. Significant CA release and 45Ca2+ uptake occurred within 1 min. Stimulation of CA release and 45Ca2+ uptake were detectable with 3 .times. 10-6 M ACh, and were inhibited by hexamethonium. Release of CA and 45Ca2+ uptake were also observed with nicotine and 1,1-dimethyl-4-phenyl-piperazinium (DMPP), but not with muscarine and methacholine. CA release and 45Ca2+ uptake apparently are mediated via stimulation of nicotinic ACh receptors. Increase in 45Ca2+ efflux was observed at lower concentrations of ACh than that required to initiate the release of CA and uptake of 45Ca2+. Increase in 45Ca2+ efflux was also observed with muscarine and methacholine, but not with nicotine and DMPP, and was inhibited by atropine, but not by hexamethonium. ACh-induced increase in 45Ca2+ efflux involves an interaction of ACh with muscarinic ACh receptors. In isolated bovine adrenal medullary cells, stimulation of nicotinic ACh receptors caused the uptake of Ca2+ by the cells which was coupled with CA release and stimulation of muscarinic ACh receptors caused the efflux of Ca2+ from the cells which was not coupled with CA release.