title: Potentiation of histamine-induced catecholamine secretion by ouabain in cultured bovine adrenal chromaffin cells is dependent on calcium and sodium influx.
abstract: The effects of histamine on catecholamine secretion from cultured bovine adrenal chromaffin cells were studied in the presence of ouabain, an inhibitor of Na+-K+ ATPase. The purpose of this study was to determine whether Na+, as well as Ca2+, was involved in histamine receptor-mediated catecholamine secretion. Histamine (10(-8)-10(-5) M)-induced catecholamine secretion was markedly potentiated by addition of ouabain (10(-5) M) and was inhibited by a histamine-H1 receptor antagonist or incubation in a Ca2+-free medium. Histamine-induced 45Ca2+ influx was also potentiated by addition of ouabain. Ouabain alone or in the presence of histamine increased 22Na+ influx into the cells. In an additional set of experiments, cells were preincubated in the presence or absence of Na+ for 30 min (+/- histamine and ouabain), washed and then catecholamine secretion was measured following exposure to 2.2 mM Ca2+ for 15 min. Preincubation with histamine alone with or without Na+ had no effect of Ca2+-induced secretion of catecholamine. Preincubation with ouabain alone or with ouabain plus histamine produced a slight stimulation of catecholamine secretion in Na+-free medium and a large stimulation in Na+-containing medium. These results suggested that stimulation of the histamine-H1 receptor and inhibition of the Na+ pump both increase intracellular Na+ levels, resulting in increases in Ca2+ influx and catecholamine secretion.
authors.affiliation: Department of Pharmacology, School of Medicine, The University of Tokushima, Kuramoto, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Houchi
authors.forename: M
authors.initials: M
authors.lastname: Yoshizumi
authors.forename: K
authors.initials: K
authors.lastname: Minakuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Ishimura
authors.forename: K
authors.initials: K
authors.lastname: Morita
authors.forename: T
authors.initials: T
authors.lastname: Tamaki
authors.forename: M
authors.initials: M
authors.lastname: Oka
mesh_terms: D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects* / Q000378:metabolism; D004357:Drug Synergism; D006632:Histamine / Q000494:pharmacology*; D017136:Ion Transport; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
chemical_list: D002395:Catecholamines; D010042:Ouabain; D006632:Histamine; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium