Figure 3 : Detection of stable isotope-labeled putrescine derived from 13C6,15N4 Arg in colonic content.

From: Upregulation of colonic luminal polyamines produced by intestinal microbiota delays senescence in mice

Figure 3

Both stable isotope-labeled putrescine (m/z 128, 171, and 361) and unlabeled putrescine (m/z 126, 166, and 355) were detected within the colonic lumen.