Paracrine renin angiotensin system in the kidney: Molecular evidence and functional significance
The recent demonstrations of renin, angiotensinogen and angiotensin converting enzyme mRNAs in the kidney provide strong evidence for the presence of an independent intrarenal RAS. Using in situ hybridization, we have localized the intrarenal sites of gene expression and possible angiotensin production. One major site appears to be the proximal tubule where local angiotensin can regulate sodium reabsorption and urine pH. Kidney angiotensinogen and renin mRNA expressions are regulated by several common factors. In particular, sodium depletion stimulates the expression of both genes in the kidney resulting in an increased production of intrarenal angiotensin that is important in maintaining sodium homeostasis. Alterations in intrarenal renin and angiotensinogen mRNA expressions may be important in the renal pathophysiology of cardiovascular diseases such as heart failure and hypertension.
