Thyroid thermogenesis: minimal contribution of energy requirement for protein synthesis.
Cycloheximide (5.0 mug/ml) had no significant effect on respiration of liver slices prepared from euthyroid rats (i.e., QO2 of 15.5 +/- 0.8 vs. 14.9 +/- 0.8 mul/mg protein) despite an 83.8 +/- 2.1% inhibition of protein synthesis as judged by [3H]leucine incorporation into the trichloroacetic acid precipitable fraction. Injection of triiodothyronine increased the QO2 of rat liver slices to 22.6 +/- 1.1 mul/h/mg protein. The QO2 of hyperthyroid slices remained high in the presence of cycloheximide although protein synthesis was inhibited by 84.4 +/- 2.0%. These results imply that the energy requirement for protein synthesis contributes little to QO2 of euthyroid liver and does not account for a significant fraction of the increase in hepatic QO2 obtained in the transition from the euthyroid to the hyperthyroid state.
D000818:Animals; D001833:Body Temperature Regulation; D003513:Cycloheximide / Q000494:pharmacology; D006358:Hot Temperature; D006980:Hyperthyroidism / Q000378:metabolism; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology*
D003513:Cycloheximide; D007930:Leucine