The renin-angiotensin system and the development of the kidney

All components of the renin-angiotensin system (RAS) (renin, angiotensinogen, angiotensins, angiotensin-converting enzyme, angiotensin II (AII) receptors - types I and 2) are present in the developing kidneys of mammals, and the genes are expressed at higher levels in fetal than postnatal life. In the last third of gestation in long-gestation mammals (primates and sheep), there is evidence from both experimental and clinical studies that a functioning RAS is required for maintained fetal urine production and thus adequate amounts of fetal fluids. The most recent evidence shows that the RAS is present in the temporary mesonephric kidney, as well as being present from very early in development of the permanent metanephric kidney. This information, together with some studies in gene-knockout mice and information from developing kidneys deprived of effective angiotensin II (AII) by drug treatment, suggests that the RAS may have a very important role in renal morphogenesis. There is now increasing evidence that the environmental milieu of the fetus, dependent largely on alterations in the maternal physiological state, can alter the susceptibility of the individual to cardiovascular and metabolic diseases many years after birth. It is, therefore, of great interest to study normal renal development and the role that the RAS may play in this process. (C) 1997, Elsevier Science Inc.