alpha GPD response to the continuous infusion of thyroxine into the hypothyroid rat.

In the present work we have studied the disappearance of the mitochondrial enzyme alpha-glycerophosphate dehydrogenase (alpha GPD) after thyroidectomy, as well as the induction by the continuous infusion of physiological doses of thyroxine to hypothyroid male rats in three different tissues, the liver, kidney and heart. Rats were previously rendered hypothyroid by surgical thyroidectomy and enzyme activity was determined at different time intervals following the ablation of the gland. Levels of alpha GPD are specifically regulated in each tissue, as both its rate of disappearance after thyroidectomy and the rate of appearance during T4 treatment are different in the liver, the kidney and the heart. Such results suggest the existence of local factors which can modify the response generated by the thyroid hormone in individual tissues.