Pericyte regulation of renal medullary blood flow

Pericytes are contractile smooth muscle-like cells that surround descending vasa recta (DVR) and provide their capability for vasomotion. The importan ce of the medullary pericyte derives from the role of DVR to distribute mos t or all of the blood flow from juxtamedullary cortex to the renal inner an d outer medulla. Physiological processes that are likely to be influenced b y pericyte constriction of DVR include the urinary concentrating mechanism and pressure natriuresis, Oxygen tensions in the medulla are low, so that s ubtle variation of pericyte vasomotion might play a role to abrogate hypoxi a and prevent insult to the medullary thick ascending limb of Henle. Known vasoconstrictors of DVR include angiotensin II, endothelins, norepinephrine , acetylcholine, and adenosine. Vasodilators include prostaglandin E-2, ade nosine, acetylcholine, bradykinin, and nitric oxide. Copyright (C) 2001 S. Karger AG, Basel.