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Query: EC:3.6.3.1 (Mg2+-ATPase)
 1,484 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The regulation of adrenergic receptors in rat heart was measured in rats made hyperthyroid by injection with thyroxine and made hypothyroid by addition of propylthiouracil to the drinking water. Hyperthyroid rats display cardiac hypertrophy and a decrease in epididymal fat pad weight. The maximal beta-receptor level of ventricular membranes, as determined by (-)-[3H]dihydroalprenolol binding, was increased 60% by thyroxine treatment and decreased about 30% by propylthiouracil treatment. The affinity of the beta receptor was unchanged after thyroxine or propylthiouracil treatment. The maximal activity of the isoproterenol-stimulated adenylate cyclase (EC 4.6.1.1) varied with thyroid state in a manner parallel to the increase in beta-adrenergic binding sites. Thyroxine treatment also increases by 2-fold the beta receptors in isolated rat fat cells. Propylthiouracil treatment lowered the level of alpha receptors in heart by 30% as measured by [3H]dihydroergocryptine binding, but increased the affinity about 2.5-fold. The highest level of alpha receptors was seen in control hearts. These studies indicate that thyroxine may control the turnover of beta-adrenergic receptors in heart and fat cells and regulate physiological responses in these tissues via a hormone-hormone interplay system. Thyroxine treatment reduced the activity of the membrane-bound Mg2+-ATPase (EC 3.6.1.3) and 5'-mononucleotidase (EC 3.1.3.5) but appears to increase the activity of the (Na+ + K+)ATPase (EC 3.6.1.4).
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PMID:Hormone action at the membrane level. VIII. Adrenergic receptors in rat heart and adipocytes and their modulation by thyroxine. 14 63

The effect of hydrocortisone and thyroxine, on the activities of Ca2+- and Mg2+- ATPase was studied in cultured neuronal (clone M1) and glial (clones NN and C6) cell lines. For M1 and NN cells an increase in Ca2+- and Mg2+-ecto-ATPase activity was found when the cells were cultured during 4-6 days in presence of hydrocortisone or together with thyroxine. In the same conditions, a decrease in Ca2+- and Mg2+-ecto-ATPase activity was found for the C6 cells. In C6 cells the effect of hormones was more pronounced for the Mg2+- than for the Ca2+-ecto-ATPase activity. The observed decrease may be related to the tumoral origin of the C6 cells. The activity of (Na+, K+)-ATPase in all three cell lines increased in presence of hydrocortisone or together with thyroxine when the cells were cultured during 4-6 days, in presence of the hormones, whereas the total Mg2+- ATPase activity increased only after 6 days of treatment. Thyroxine alone has very few effect either on Ca2+- and Mg2+-ecto-ATPase, or on (Na+, K+)- and total Mg2+-ATPase activity. These observations are interpreted to indicate that hormones may modulate or induce enzymatic activities involved in active transport phenomena in nervous tissue.
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PMID:Effect of hydrocortisone and thyroxine on ATPase activities of neuronal and glial cell lines in culture. 612 4