The intrarenal renin-angiotensin system: a paracrine system for the local control of renal function separate from the systemic axis.

The kidney serves an integral role in the systemic renin-angiotensin system (RAS) both as an effector and as a target organ. Increasing evidence also accumulates that local intrarenal RAS serve as important regulators of renal function. Evidence is reviewed concerning the expression and potential role of components of the RAS in glomeruli, proximal tubule and renal interstitium. In addition to regulating normal renal function, local renal RAS may be triggered in response to renal injury and may contribute to structural and functional abnormalities, including increased glomerulosclerosis and tubulointerstitial fibrosis.