[Action of thyroid hormones and somatotropin on the free radical, iron-sulfur protein and cytochrome P-450 state in the liver].

The state of free radicals, iron-sulphuric proteins and cytochrome P-450 was determined in hypo- and hyperthyroid rats by means of EPR method. It was shown that EPR signal of cytochrome P-450 was increased in the liver of thyroidectomized rats, characterized by somatotropin deficiency and delayed metabolism. It decreased under the action of exogenous somatotropin both in intact and in thyroidectomized animals. Cytochrome P-450 was lowered in hyperthyroid rats, characterized by intensified oxidative processes without signs of the enhanced hepatic growth. The feedback between the intensified hepatic oxidative processes and the activity of cytochrome P-450-dependent multipurposeful oxidases is suggested.