[Experimental thyrotoxicosis under conditions preventin hyperlipacidemia]

Prolonged administration to rabbits of nicotinic acid was accompanied by a fall in glucogen level in the liver and hyperglycemia. Consumption of O2 by the animals, their weight, and also the volume circulation along the main vessels and the pulse frequency remained unchanged. Thyroidin administration to rabbits led to increase in the content of free fatty acids (FFA) in the plasma, reduction in the glycogen level in the liver and the myocardium a sharp fall in body weight of the animals, an increase of O2 consumption by them, tachycardia and an increase in the volume circulation. A simultaneous administration of thyroidin and nicotinic acid blocked an increase in the FFA level in the plasma and led to a greater fall in the glycogen content in the liver, but failed to alter any other manifestations of thyrotoxicosis. The authors concluded that the thyrotoxic hypermetabolism was independent of increase in the blood FFA level and their tissue oxidation. Various mechanisms of the calorigenic effects of catecholamines and of the thyroid hormones are analyzed; it is supposed that hypermetabolism of any genesis had an increase of free thyroid hormones in the blood as the common final link of its development.