title: Angiotensin II metabolism by tissues from developing rats.
abstract: Asp1-125I-Tyr4-angiotensin II (125I-AII) was degraded during incubation with rat plasma or homogenates of liver or kidney. The electrophoretic profile of peptide fragments revealed that the disappearance of 125I-AII was first order and was accompanied by an accumulation of 125I-tyrosine in the incubation medium. The only other metabolites of angiotensin AII detectable by peptide mapping 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 angiotensin II hydrolysis. The half-life of 125-AII in plasma or liver homogenates did not change with age (approximately 8 to 12 and 6 to 9 min, respectively). In contrast, the rate of disappearance of 125I-AII in homogenates of rat kidney depended upon the age of the rat from which the tissue was obtained. The half-life of 125AII decreased three-fold (from approximately 8.3 to 2.8 min) between 2 wk after birth and adult (approximately 8 wk). This increase in the rate of metabolism of 125I-AII was accompanied by a concomitant two-fold, age-related increase in the rate of appearance of 125I-tyrosine in the reaction mixture containing renal tissue.
mesh_terms: D000375:Aging; D000804:Angiotensin II / Q000097:blood / Q000378:metabolism*; D000818:Animals; D010450:Endopeptidases / Q000378:metabolism; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010446:Peptide Fragments / Q000032:analysis; D051381:Rats
chemical_list: D010446:Peptide Fragments; D000804:Angiotensin II; D010450:Endopeptidases