In vivo and in vitro effects of adrenaline on conversion of thyroxine to triiodothyronine and to reverse‐triiodothyronine in dog liver and heart

Abstract

Adrenaline [epinephrine, E] infusion in healthy dogs in a dose simulating spontaneous release of the catecholamine during experimental myocardial infarction produced a significant decrease in the conversion of thyroxine (T4) to triiodothyronine (T3) and a moderate increase in the conversion of T4 to reverse-T3 (rT3). Similar changes in deiodination of T4 to T3 and to rT3 were also observed when E was added in vitro to liver and heart homogenates. These results are consistent with a direct effect of E on T4 deiodination as degradation of exogenous T4, T3 and rT3 was only slightly increased under the experimental condition employed. Increased tissue exposure to E might contribute to the hormonal changes seen in at least some cases of the low T3 syndrome.