Biliary Excretion of Thyroid Hormones in Heat-Exposed Rats ∗

Abstract

Summary

Heat-exposed rats gained less weight, consumed less food, and, when bile was collected, secreted less bile than the controls. When heat-exposed rats were injected with ¹³¹I-T₄, this hormone was excreted into the animals'bile at the same rate as exogenous ¹³¹I-T₄ is eliminated in controls. However, heat-exposed rats cleared less plasma per unit time of endogenous ¹³¹I-thyroid hormones than did normal controls. It was concluded that this decrease in hepatic secretion of endogenous labeled ¹³¹I-thyroid hormones is not due to the observed reduction in bile flow in heat-exposed rats, since a choleretic did not increase biliary clearance of ¹³¹I in heat-exposed rats.