THE EFFECT OF EPINEPHRINE AND NOR-EPINEPHRINE ON THE ACUTE THYROID RELEASE OF THYROID HORMONES

Abstract

Catheterization of the thyroid vein and measurement of its PBI131 levels have been utilized to study the effect of epinephrine and nor-epinephrine on the release of thyroid hormones from the thyroid in dogs. After intravenous administration of epinephrine to seven dogs and of nor-epinephrine to three dogs, increases in PBI131 levels from 1.5 to 17.1 times the control values were found. These responses occurred within 15 to 95 minutes in all dogs tested. Control experiments in three dogs have shown that during a comparable experimental period of four hours, no significant change in thyroid venous PBI131 concentrations took place. In two dogs given thyroid stimulating hormone (TSH) intravenously, increases in thyroid venous PBI131 levels of 18.9 and 7.4 times the control activities were noted. The initial responses occurred within 20 minutes after starting the TSH infusion. In two hypophysectomized dogs, epinephrine infusion was attended with a rise in thyroid venous PBI131 comparable to that seen in the intact animal. These data would indicate that the stimulating effect of epinephrine is exerted directly on the thyroid gland. Preliminary radio-paperchromatographic studies in one dog revealed that the increase of PBI131 observed in the thyroid vein during epinephrine stimulation was attributable to rises in both thyroxine and triiodothyronine. The possible participation of increased hormonal secretion from the thyroid gland in the acute metabolic response to stress has been discussed in the light of these data.