Open AccessInhibition by chlorpromazine, metals and I-ascorbic acid of calcium-ATPase and magnesium-ATPase in bovine adrenal medullary microsomes.
Author(s) -
Kyozo Yamanaka,
Shizuo Yamada,
Satoru Hayashi,
Eiichi Hayashi
Publication year - 1984
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.34.447
Subject(s) - microsome , atpase , chemistry , ascorbic acid , chlorpromazine , calcium , biochemistry , calcium atpase , adrenal medulla , medicine , endocrinology , enzyme , biology , catecholamine , food science , organic chemistry
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.