Regulation of adenosine 3',5'-monophosphate content in human astrocytoma cells by isoproterenol and carbachol
Gross, R.A.; Clark, R.B.
Molecular Pharmacology 13(2): 242-250
1977
ISSN/ISBN: 0026-895X PMID: 192991 Document Number: 117345
Carbachol, a typical cholinomimetic, inhibited isoproterenol stimulation of intracellular cAMP levels in a dose dependent fashion, causing a maximal 60-70% decrease at 0.1 mM. The blocking action of carbachol was evident by 30 s, and reached a maximum between 5 and 7 min. Neither lidocaine, a local anesthetic, nor ascorbic acid and thiourea, reducing agenst, had any effect on the action of carbachol. Carbachol inhibited the accumulation of cAMP caused by isoproterenol, adenosine, and prostaglandin E1. Neither hexamethonium bromide, tetraethylammonium chloride, nor phentolamine affected the regulation of cAMP levels by carbachol. In contrast, 1.0 .mu.M atropine completely blocked its effects. Ca2+-free incubation medium eliminated the inhibitory effect of carbachol on isoproterenol stimulated accumulation of cAMP, but did not affect isoproterenol stimulation alone. The astrocytoma cell line probably has a muscarinic, Ca2+-dependent cholinergic receptor, the stimulation of which results in inhibition of cAMP accumulation with isoproterenol stimulation.