Renin exists in high concentration in the adrenal gland of the rat

Renin-like activity was detected in various endocrine glands and other extrarenal tissues. Both nonspecific proteolytic activity of proteases and the specific action of renin contribute to this activity. In order to estimate the true renin component in these extrarenal tissues of rats, we determined the renin activity which is sensitive to inhibition by a specific antibody produced against pure rat renal renin. A widespread distribution of true renin was revealed. The adrenal gland was found to have the highest true renin activity per unit weight of protein among the various extrarenal tissues. Its activity was several thousand times as great as the other tissues and was only one fifteenth of that in the renal cortex. The pH optimum of this adrenal renin was approximately 7.0. These findings suggest a control mechanism for adrenal function mediated by an intraadrenal renin-angiotensin system in addition to the plasma renin-angiotensin system.