title: Postnatal development of the renin-angiotensin system in rats.
abstract: The purpose of this investigation was to correlate the development of the various enzyme activities associated with the renin-angiotensin system with age-related differences in the steady-state concentrations of angiotensin I (AI) and II (AII). Angiotensin was quantified by radioimmunoassay. Plasma renin activity and concentration increased between birth and 3 wk of age, and declined thereafter to adult values. Renal renin content, on the other hand, increased throughout the first 6 wk of postnatal life. The concentration of AII in plasma also increased following birth; however, maximum concentrations were not attained until 5 wk of age. In contrast, plasma AI did not increase between 3 and 6 wk of age. These data suggest that the steady-state concentration of AII in neonatal rat plasma may be partially limited by the low plasma renin substrate concentration. The increase in AII between 3 and 6 wk of age may reflect the increasing converting enzyme activity.
mesh_terms: D000375:Aging; D000803:Angiotensin I / Q000378:metabolism; D000804:Angiotensin II / Q000097:blood*; D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D010450:Endopeptidases / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D051381:Rats / Q000097:blood*; D012083:Renin / Q000378:metabolism
chemical_list: D000804:Angiotensin II; D000803:Angiotensin I; D010450:Endopeptidases; D012083:Renin