[Effect of thyroxine on oxidative enzymatic activity in the rat aorta].

The activity of hexokinase, dehydrogenases of pentose cycle, total lactate dehydrogenase, and cytochrome-C-oxidase level was determined in the aorta of rats with hyperthyroidism caused by the intraperitoneal administration of L-thyroxin. In the administration of hormone doses approaching the physiological ones there was an increase in the activity of cytochrome-C-oxidase and a tendency to the increase of 6-phosphogluconate dehydrogenase. Elevation of the activity of all the enzymes under study, excluding lactate dehydrogenase, and in increase of the amount of extractable protein occurred in the administration of moderate thyroxin doses. An increase of hexokinase and particularly of cytochrome-C-oxidase activity was revealed in hyperthyroidism with phenomena of thyrotoxicosis. The activity of the rest of the enzymes approached control. The data obtained are discussed from the point of view of the role played by thyroid hormones in the pathogenesis of atherosclerosis.