title: Magnesium but not calcium accumulation is inhibited by beta-adrenergic stimulation in S49 lymphoma cells.
abstract: The uptake of 28Mg and 45Ca was measured in S49 lymphoma cells. The beta-adrenergic agonist (-)-isoproterenol markedly inhibited the rate of 28Mg accumulation but had no effect on 45Ca accumulation. The effect of (-)-isoproterenol was blocked by (-)-propranolol. In variants of the S49 cell line deficient in adenylate cyclase activity (cyc-) or in hormone receptor-adenylate cyclase coupling (unc), (-)-isoproterenol had no effect on 28Mg accumulation. The S49 lymphoma cells also possess prostaglandin E1 receptors coupled to adenylate cyclase, and, like (-)-isoproterenol, prostaglandin E1 decreased the rate of 28Mg uptake. Experiments with the mouse erythroleukemia cell line GM86 also showed a beta-adrenergic-mediated decrease in the rate of accumulation of 28Mg. Previous work has shown that Mg2+ increases the affinity of agonists for the beta-adrenergic receptor (Bird, S.J., and Maguire, M.E. (1978) J. Biol. Chem. 253, in press). In view of these effects of Mg2+, it is suggested that Mg2+, but not Ca2+, may regulate the sensitivity of S49 cell adenylate cyclase to stimulation by catecholamines.
mesh_terms: D001693:Biological Transport, Active / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology*; D011458:Prostaglandins E / Q000494:pharmacology
chemical_list: D011458:Prostaglandins E; D010042:Ouabain; D011433:Propranolol; D008274:Magnesium; D007545:Isoproterenol; D002118:Calcium