[Thyroid hormones and EPR signals of the liver, brain and blood]

Experimental hypothyreosis was caused by thyroidectomy, hyperthyreosis developed after intraperitoneal administration of thyroxine into animals within 10 days. In liver and brain preparations amplitudes of EPR signals were decreased with g = 2.00 and g = 1.94, respectively, in hypothyreosis and were increased in hyperthyreosis. The ratio of these signals amplitudes was unaltered in brain tissue but in liver tissue it varied depending on thyroid status. In liver tissue intensity of other signals was increased in hyperthyreosis ad decreased in hypothyreosis, except for the signal with g = 2.25 (cytochrome P = 450) the intensity of which decreased in hyperthyreosis and increased in hypothyreosis. These phenomena appear to be relevant to various disorders of metabolism in pathologies of thyroid glands.