Metabolism of creatinine in vivo.
Two forms of radiolabeled creatinine were used in this study, [carbonyl-14C]- and [amidino-14C]creatinine, the latter being synthesized in this laboratory. These labeled compounds were given intravenously to rabbits. Specimens of plasma, urine, feces, and selected tissues were collected. These were liquid-chromatographed and the separated components compared for radioactivity and identity. This first use of amidino-labeled creatinine revealed the metabolic conversion of small amounts of creatinine to an unidentified non-basic compound and guanidinobutyrate in normal rabbits and to guanidinopropionic acid and arginine in a rabbit that had a low creatinine clearance. A mechanism is suggested for this metabolic process. The proposed pathway may be a major route of elimination of creatinine in renal failure.
D000818:Animals; D001120:Arginine / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000032:analysis / Q000378:metabolism*; D005243:Feces / Q000032:analysis; D006146:Guanidines / Q000378:metabolism; D009132:Muscles / Q000032:analysis; D011422:Propionates / Q000378:metabolism; D011817:Rabbits; D014511:Uremia / Q000378:metabolism
D006146:Guanidines; D011422:Propionates; C032267:beta-guanidinobutyric acid; D001120:Arginine; D003404:Creatinine; C005775:guanidinopropionic acid