The effect of prolactin on human aldosterone-producing adenomas in vitro

There is evidence for an unidentified aldosterone-stimulating factor of pituitary origin. We measured the effect of ovine PRL (oPRL) on aldosterone secretion by isolated cell suspensions of human aldosterone-producing adenomas (APAs) and compared it to the effects of angiotensins, ACTH, and potassium (K+). In the first APA, the aldosteronotropic action of large doses of oPRL was double that of angiotensin II (AII); the response to ACTH was triple that to AII, while K+ had a small stimulatory effect. Results with the second APA showed that physiological concentrations of oPRL caused a response nearly double that to AII, but, once again, less than the response to ACTH; K+ was inert. ACTH contamination of the oPRL preparation was too minute to account for these findings. We conclude that oPRL possesses aldosterone-stimulating activity in APAs greater than that of angiotensins and potassium, but less that that of ACTH. These data suggest a role for PRL in aldosterone secretion by aldosterone-producing adenomas.