Stimulation of specific [3H]-ouabain binding to microsomal preparations from rat heart and skeletal muscle by thyroid hormones: effects of 6-hydroxydopamine.
1. Surgical thyroidectomy decreased specific [3H]-ouabain binding to heart ventricular microsomes by 43% and gastrocnemius muscle microsomes by 34%. Administration of triiodothyronine to euthyroid rats enhanced specific [3H]-ouabain binding to heart and skeletal muscle membrane by 60% and 33% respectively. 2. Treatment of thyroidectomized rats with triiodothyronine increased specific [3H]-ouabain binding by 44% in skeletal muscle membrane preparation and 428% in cardiac microsomes. 3. Specific [3H]-ouabain binding decreased by 55% in heart and 53% in gastrocnemius muscle preparations following chemical sympathectomy with 6-hydroxydopamine. 4. Treatment with triiodothyronine of euthyroid rats which had been sympathectomized did not significantly alter specific [3H]-ouabain binding to heart or skeletal muscle membrane preparations. 5. Administration of triiodothyronine to thyroidectomized and sympathectomized rats increased specific [3H]-ouabain binding by 80% in heart and 83% in skeletal muscle membrane preparations. 6. These results suggest that triiodothyronine may influence specific [3H]-ouabain binding to thyroid hormone nonresponsive tissue such as sympathetic nerve endings. Therefore, the present observations are incompatible with the hypothesis that induction of (Na+ +K+)-adenosine triphosphatase of skeletal muscle membrane is the molecular mechanism for the calorigenic actions of thyroid hormones.
D000818:Animals; D004347:Drug Interactions; D006892:Hydroxydopamines / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D010042:Ouabain / Q000378:metabolism*; D051381:Rats; D013965:Thyroidectomy; D014284:Triiodothyronine / Q000494:pharmacology*
D006892:Hydroxydopamines; D014284:Triiodothyronine; D010042:Ouabain