Gut microbiota in rats injected with isotope-labelled arginine via a catheter.

Male Crl:CD (SD) rats (eight weeks of age) fitted with proximal colon catheters were purchased from Charles River Laboratories Japan, Inc. (Kanagawa, Japan). Animals were housed individually in 263 ? 420 ? 20 mm plastic cages under a 12 h light/dark cycle at 25 ? 1?C in conventional conditions, and provided standard pellet chow and water ad libitum. Isotope labelled L-arginine-13C6,15N4 1 HCl in saline pH 7.0 was injected into rats (n = 3) via a colon catheter at 6.6 mg/kg body weight. Rats were euthanised 6 h post-injection, and the contents of the colon were collected to analyse bacterial composition. In this study, our goal was to investigate intestinal bacteria involved in collective metabolic pathway of putrescine from arginine in the colonic lumen.