Renal medullary system of blood pressure control.

The renal medulla contains cells in its papillary portion, the renomedullary interstitial cells (RIC), that secrete a blood pressure-controlling hormone. This hormone system has been identified by classic types of experiments as developed by Bayliss and Starling, Goldblatt, Byrom and Dodson and Berthold. The antihypertensive neutral renomedullary lipid is the putative hormone. This hormonal system is antagonized by angiotensin II. It antagonizes the blood pressure (BP) elevating effects of salt.