title: Inhibition by chlorpromazine, metals and I-ascorbic acid of calcium-ATPase and magnesium-ATPase in bovine adrenal medullary microsomes.
abstract: Effects of chlorpromazine, metals and I-ascorbic acid (AA) on Ca2+-ATPase and Mg2+-ATPase in microsomal and granular fractions obtained from the bovine adrenal medulla were studied. Marker enzyme analysis on microsomal subfractions in a discontinuous sucrose density gradient showed a correlation of distribution between ATPase activities and plasma membrane. The two ATPase activities in such plasma membrane-rich microsomes were reduced by chlorpromazine, Hg2+ and Cu2+ (0.3 mM of each), and their effects were greater on the Mg2+-ATPase activity. Zn2+ (0.3 mM) also reduced only the Mg2+-ATPase activity. AA (3 mM) reduced the two ATPase activities to an equal extent. Nevertheless, the inhibitions of ATPases by Hg2+, Cu2+ and Zn2+ were decreased, unaltered and additively enhanced in combination with AA, respectively. We also observed high Mg2+-ATPase activity in the granule-rich fraction, but this ATPase activity was unaffected by all of the above agents. These results indicate that Mg2+-ATPase in the plasma membrane-rich microsome of adrenal medulla is inhibited by chlorpromazine, Hg2+, Cu2+ and Zn2+ more significantly than Ca2+-ATPase, but Mg2+-ATPase in the granular fraction is unaffected, and that AA changes the potency of inhibition by some metals of ATPases diversely.
mesh_terms: D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000313:Adrenal Medulla / Q000201:enzymology* / Q000648:ultrastructure; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D002746:Chlorpromazine / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D066298:In Vitro Techniques; D008628:Mercury / Q000494:pharmacology; D008670:Metals / Q000494:pharmacology*; D008861:Microsomes / Q000201:enzymology*; D015032:Zinc / Q000494:pharmacology
chemical_list: D008670:Metals; D003300:Copper; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D008628:Mercury; D015032:Zinc; D001205:Ascorbic Acid; D002746:Chlorpromazine