Abstract
In order to attempt to account for age-related differences in plasma angiotensin II concentration, the activity of angiotensinases in developing rat tissues was examined. The rate of degradation of A-II was determined in vitro during incubation of tissue homogenates with 125-I-tyrosine labeled angiotensin II. Peptide fragments were separated electrophoretically and quantified by gamma scintillation counting. Half-life of labeled A-II in plasma or liver homogenates did not change with age. In contrast, the half-life in renal tissue homogenates decreased from 8.4 ± 1.2 minutes in two-week-old rats to 4.7 ± 0.7 minutes in eight-week-old rats and 2.8 ± 1.8 minutes in adults. This change in the rate of disappearance was accompanied by concomitant increase in the rate of appearance of labeled peptide fragments. Peptide mapping revealed that the principal metabolite of 125-AII was tyrosine. The only other detectable metabolites of A-II were the amino-terminus tetrapeptide and the carboxy-terminus hexapeptide. The appearance of these fragments was highly variable, suggesting that endopeptidases did not constitute the ultimate cleavage of All degradation. The increased rate of metabolism of angiotensin II during development is consistent with the age-related increases in the concentration of angiotensin II in plasma of developing rats as demonstrated by previous studies from our laboratory.(Supported by NIH Grants HD06290 & HL22544)
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Bailie, M., Wallace, K. & Oparil, S. AGE RELATED DIFFERENCES IN ANGIOTENSIN II (A-II) METABOLISM IN RAT TISSUES. Pediatr Res 14, 986 (1980). https://doi.org/10.1203/00006450-198008000-00076
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DOI: https://doi.org/10.1203/00006450-198008000-00076
