RT Journal Article SR Electronic T1 Specific [3H]Ouabain Binding to Rat Heart and Skeletal Muscle: Effects of Thyroidectomy JF Molecular Pharmacology JO Mol Pharmacol FD American Society for Pharmacology and Experimental Therapeutics SP 122 OP 129 VO 14 IS 1 A1 VIRENDRA K. SHARMA A1 SHAILESH P. BANERJEE YR 1978 UL http://molpharm.aspetjournals.org/content/14/1/122.abstract AB Administration of triiodothyronine increased specific [3H]ouabain binding by 46% in gastrocnemius muscle and 54% in heart ventricle muscle microsomal suspensions derived from euthyroid rats. Thyroidectomy decreased specific [3H]ouabain binding by 37% and 56% in skeletal and heart muscle microsomes, respectively. Administration of triiodothyronine to thyroidectomized rats increased specific [3H]ouabain binding by 69% in gastrocnemius muscle and 425% in cardiac muscle membrane preparations. Scatchard analysis revealed that regulation of specific [3H]ouabain binding sites by triiodothyronine is mediated by alterations of dissociation constants and not by changes in the maximal number of binding sites. These observations are incompatible with the hypothesis that induction of (Na+ + K+)-ATPase of cardiac and skeletal muscle membrane is the molecular mechanism for the thermogenic action of thyroid hormones. ACKNOWLEDGMENTS The authors thank Ms. Lily S. Kung for measuring ATP hydrolytic activity in cardiac microsomal suspensions.