Renal medulla: an endocrine organ involved in blood pressure regulation.

The renal medulla is not often considered an endocrine organ, but recent evidence suggests that this part of the kidney may have important antihypertensive, endocrine functions. The antihypertensive factor(s) of the medulla have been localized to the interstitial cells and characterized as neutral and acidic lipids. The acidic lipids, or protstaglandins, have been the more extensively investigated. Animal and human studies indicate that prostaglandins may influence systemic arterial pressure directly or indirectly by promoting excretion of salt and water. Recent evidence suggests that prostaglandins may be mediators of the renin-angiotensin-aldosterone system, thus influencing blood pressure via this system that plays such a key role in blood pressure control.