Noradrenaline and thyroid function regulate (Na+,K+)-adenosine triphosphatase independently in vivo.
We investigated interactions between noradrenaline and thyroid hormone status in the regulation of (Na+,K+)-ATPase in vivo. Treatment with the beta-adrenoceptor antagonist propranolol or with the neurotoxin 6-hydroxydopamine did not prevent the increases in heart (Na+,K+)-ATPase associated with triiodothyronine treatment. Administration of methimazole did not prevent the increase in (Na+,K+)-ATPase indices in cerebral cortex and heart associated with subacute noradrenergic stimulation by yohimbine. There was no evidence for synergistic effects between thyroid hormone administration and noradrenergic stimulation by yohimbine. Thyroid hormone, unlike noradrenaline, mainly increased (Na+,K+)-ATPase activity with low affinity for ouabain. These results show that noradrenaline and thyroid hormone regulate (Na+,K+)-ATPase by largely independent mechanisms, and may regulate different populations of enzyme molecules.
Swann
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AC
Department of Psychiatry, University of Texas Medical School, Houston 77225.
D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D006892:Hydroxydopamines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D008713:Methimazole / Q000494:pharmacology; D009206:Myocardium / Q000201:enzymology; D009638:Norepinephrine / Q000494:pharmacology*; D010042:Ouabain / Q000378:metabolism; D016627:Oxidopamine; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013961:Thyroid Gland / Q000502:physiology*; D014284:Triiodothyronine / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D006892:Hydroxydopamines; D014284:Triiodothyronine; D015016:Yohimbine; D008713:Methimazole; D010042:Ouabain; D016627:Oxidopamine; D011433:Propranolol; D009597:4-Nitrophenylphosphatase; D000254:Sodium-Potassium-Exchanging ATPase; D009638:Norepinephrine