Implication of creatinine and gut flora in the uremic syndrome: induction of "creatininase" in colon contents of the rat by dietary creatinine.

“Creatininase” activity was induced in the colon flora of rats by feeding creatinine. Sarcosine and methylamine were tentatively identified as the major products of the enzymic action. A third (unidentified) compound was observed. These compounds and methylguanidine were labeled in the urine of rats given ‘CH3-creatinine orally. The resuits suggest that creatinine should not be considered biologically inert in animals, especially in those with decreased renal function.