title: Mg2+- or Ca2+-activated ATPase activities of plasma membranes isolated from vascular smooth muscle.
abstract: Studies of ATP hydrolysis by various subcellular fractions isolated from rat mesenteric arteries and veins indicate that an apparent ATPase activity, which can be activated by Mg2+ or Ca2+, is primarily associated with the plasma membranes. Although both Mg2+-activated and Ca2+-activated ATPase activities under the optimal condition are substantially lower in venous than in arterial plasma membrane fraction, their dependence on the concentration of Mg2+ and Ca2+ are quite similar in arterial as well as venous plasma membrane fractions. No synergistic effect on ATP hydrolysis was observed in the presence of both Mg2+ and Ca2+. In addition, Mg2+-activated and Ca2+-activated ATPase activities show similar pH dependence, inhibition by deoxycholate, stability toward heat inactivation and substrate specificity. Furthermore, Mg2+-activated and Ca2+-activated ATPase activities were similarly reduced in vascular smooth muscles of spontaneously hypertensive rats. These results suggest that the activation of ATP hydrolysis by Mg2+ or Ca2+ may represent a single enzyme moiety in the plasma membrane of vascular smooth muscle. The possible involvement of such ATPase in the Ca2+ transport function of vascular smooth muscle is discussed.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002462:Cell Membrane / Q000201:enzymology; D003840:Deoxycholic Acid / Q000494:pharmacology; D005260:Female; D006973:Hypertension / Q000201:enzymology; D066298:In Vitro Techniques; D008297:Male; D008670:Metals / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology; D014638:Vanadates; D014639:Vanadium / Q000494:pharmacology
chemical_list: D008670:Metals; D011506:Proteins; D003840:Deoxycholic Acid; D014639:Vanadium; D014638:Vanadates; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases