title: Sulfate-reducing bacteria slow intestinal transit in a bismuth-reversible fashion in mice.
abstract: BACKGROUND
  Hydrogen sulfide (H2S) serves as a mammalian cell-derived gaseous neurotransmitter. The intestines are exposed to a second source of this gas by sulfate-reducing bacteria (SRB). Bismuth subsalicylate binds H2S rendering it insoluble. The aim of this study was to test the hypothesis that SRB may slow intestinal transit in a bismuth-reversible fashion.
  
  
  METHODS
  Eighty mice were randomized to five groups consisting of Live SRB, Killed SRB, SRB+Bismuth, Bismuth, and Saline. Desulfovibrio vulgaris, a common strain of SRB, was administered by gavage at the dose of 1.0 × 109cells along with rhodamine, a fluorescent dye. Intestinal transit was measured 50 minutes after gavage by euthanizing the animals, removing the small intestine between the pyloric sphincter and the ileocecal valve and visualizing the distribution of rhodamine across the intestine using an imaging system (IVIS, Perkin-Elmer). Intestinal transit (n=50) was compared using geometric center (1=minimal movement, 100=maximal movement). H2S concentration (n=30) was also measured when small intestinal luminal content was allowed to generate this gas.
  
  
  RESULTS
  The Live SRB group had slower intestinal transit as represented by a geometric center score of 40.2 ± 5.7 when compared to Saline: 73.6 ± 5.7, Killed SRB: 77.9 ± 6.9, SRB+Bismuth: 81.0 ± 2.0, and Bismuth: 73.3 ± 4.2 (P<.0001). Correspondingly, the Live SRB group had the highest luminal H2S concentration of 4181.0 ± 968.0 ppb compared to 0 ± 0 ppb for the SRB+Bismuth group (P<.0001).
  
  
  CONCLUSIONS
  Live SRB slow intestinal transit in a bismuth-reversible fashion in mice. Our results demonstrate that intestinal transit is slowed by SRB and this effect could be abolished by H2S-binding bismuth.
authors.affiliation: Section of Gastroenterology, New Mexico VA Health Care System, Albuquerque, NM, USA.|Department of Biology, University of New Mexico, Albuquerque, NM, USA.
authors.forename: N L
authors.initials: NL
authors.lastname: Ritz
authors.affiliation: Section of Gastroenterology, New Mexico VA Health Care System, Albuquerque, NM, USA.
authors.forename: D M
authors.initials: DM
authors.lastname: Lin
authors.affiliation: Section of Gastroenterology, New Mexico VA Health Care System, Albuquerque, NM, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Wilson
authors.affiliation: Department of Biology, University of New Mexico, Albuquerque, NM, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Barton
authors.affiliation: Section of Gastroenterology, New Mexico VA Health Care System, Albuquerque, NM, USA.|Department of Medicine, University of New Mexico, Albuquerque, NM, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000818:Animals; D001729:Bismuth / Q000494:pharmacology*; D016969:Desulfovibrio vulgaris / Q000378:metabolism*; D005260:Female; D005772:Gastrointestinal Transit / Q000187:drug effects / Q000502:physiology*; D006862:Hydrogen Sulfide / Q000378:metabolism*; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009942:Organometallic Compounds / Q000494:pharmacology*; D011897:Random Allocation; D012459:Salicylates / Q000494:pharmacology*
chemical_list: D009942:Organometallic Compounds; D012459:Salicylates; C015715:bismuth subsalicylate; D001729:Bismuth; D006862:Hydrogen Sulfide
keywords: hydrogen sulfide; microbiome; motility; transit