Secretion of Aldosterone by Adrenal Glands of Propylthiouracil-Treated Rats

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Abstract
Dietary administration of the antithyroid drug, propylthiouracil (PTU), to rats for 20 weeks reduced rate of secretion of aldosterone 26% (m[mu]g/min/adrenal/100 g body wt) to 69% (m[mu]g/min/ adrenal) below that of euthyroid controls. Reduction in rate of secretion of aldosterone occurred in association with reduced adrenal blood flow as well as with reduced total pressor activity of kidneys (assumed to be renin). The latter was the result of smaller kidneys of treated rats rather than a reduction of unit concentration of the pressor material. Rate of metabolism of deoxycorticosterone by liver slices of PTU-treated rats (both unit and total activity) was similar to that of euthyroid controls. Hence, reduced rate of secretion of aldosterone by adrenals of PTU-treated rats was apparently not associated with reduced rate of hepatic metabolism of the hormone. Daily administration of 8-10 [mu]g thyroxine/100 g body wt to PTU-treated rats for 2 weeks returned rate of secretion of aldosterone to that of euthyroid controls. These studies suggest that thyroxine plays a greater role in regulation of adrenal cortical secretion of aldosterone than heretofore suspected.