CIN '2007 - 4th CONGRESS OF NEPHROLOGY IN INTERNET
Vitamin D Regulation of the Renin-Angiotensin System: Mechanism and Implications
Dr. Yan Chun Li, Ph.D.
Department of Medicine. University of Chicago. Chicago, IL
Abstract
The renin-angiotensin system (RAS) plays a central role in the regulation of blood pressure, electrolyte and volume homeostasis. The RAS is a cascade that leads to the generation of angiotensin II (Ang II), the main effector of the RAS. The rate-limiting component of the RAS is renin, a highly specific aspartic peptidase synthesized and secreted predominantly by the juxtaglomerular (JG) cells in the nephron. The only known substrate of renin is angiotensinogen, which is enzymatically cleaved to angiotensin I by renin. Angiotensin I is further cleaved to Ang II by the angiotensin-converting enzyme (ACE). The main physiological role of Ang II is to regulate blood pressure, electrolyte and extracellular volume. Over-activation of the RAS leads to hypertension and end organ damage. Ang II is also known to be involved in such pathological conditions as fibrogenesis, atherogenesis, hypertrophy, inflammation and proliferation (Fig. 1).Comments: