Intrarenal Renin-Angiotensin System

Abstract

The actions of angiotensin II in the kidney are often described in terms of the intrarenal RAS; a recent symposium carried the title “Physiological Role of the Intrarenal Renin-Angiotensin System” (Navar 1986). Obviously, the intention of using this term is to suggest that the intrarenal effects of angiotensin II are not, or not exclusively, mediated by systemically generated angiotensin II reaching the kidney via the circulation but rather by intrarenally formed angiotensin II. However, beyond the general agreement that local angiotensin II formation in the kidney occurs, there is considerable uncertainty and disagreement on the understanding of an intrarenal RAS. Therefore, we will first discuss briefly the characteristics of locally functioning RASs in general, consider the potential for the intrarenal formation of angiotensin II, then proceed to describe the intrarenal actions of exogenous and endogenous angiotensin II, and finally return to the consideration of whether an intrarenal RAS exists.