Mineralocorticoid activity of 19-nor-DOC and 19-OH-DOC in adrenalectomized rat

Excess mineralocorticoid activity is thought to be responsible for the increased sodium reabsorption found after adrenal enucleation, but no known mineralocorticoid has been demonstrated in quantities sufficient to account for this antinatriuresis. 19-Hydroxydeoxycorticosterone (19-OH-DOC) has been synthesized by the incubated enucleate adrenal capsule and 19-nordeoxycorticosterone (19-nor-DOC), a possible metabolite, has been found in the urine of rats with regenerating adrenal glands. To evaluate the in vivo mineralocorticoid potency of these steroids, we studied glucocorticoid-replete adrenalectomized rats and measured the sodium and potassium excretion after administration of these steroids. Our results indicate that 19-nor-DOC has equipotent antinatriuretic activity compared to aldosterone but was less kaluretic. 19-OH-DOC had no significant antinatriuretic or kaluretic activity. We conclude that 19-nor-DOC is a potent mineralocorticoid and may be responsible for the enhanced sodium reabsorption found after adrenal enucleation.