title: Mucosal adenosine triphosphate mediates serotonin release from ileal but not colonic guinea pig enterochromaffin cells.
abstract: BACKGROUND
  Mechanical stimulation of the mucosal epithelium results in increased serotonin (5-HT) release from enterochromaffin (EC) cells. Little is known about how this process varies in different regions of the intestinal tract; however, purines are felt to play a role. We studied the relationship between mechanical stimulation, adenosine triphosphate (ATP), and 5-HT release from ileal and colonic mucosal tissue.
  
  
  METHODS
  Amperometric recordings of ATP and 5-HT were carried out using an ATP biosensor and boron-doped diamond microelectrode. Levels of extracellular ATP and 5-HT were monitored using high performance liquid chromatography.
  
  
  RESULTS
  Under basal conditions, 5-HT levels were significantly decreased in the ileum (p < 0.001) but not the colon in the presence of the P2 antagonist suramin (100 μM). Ecto-ATPase inhibitor ARL67156 (10 μM) elevated ATP levels in the ileum and colon (both p < 0.001), but only 5-HT levels in the ileum (p < 0.001). Exogenous ATP increased 5-HT release in the presence of tetrodotoxin in the ileum (p < 0.001), but had not effect in the colon. Mechanical stimulation increased levels of 5-HT in the ileum (p < 0.001) and colon (p < 0.01), but levels returned to baseline in the presence of suramin and MRS2179 in the ileum. The onset of 5-HT release was delayed following mechanical stimulation. The rise time of the ATP response was quicker than that of 5-HT during mechanical stimulation.
  
  
  CONCLUSIONS
  During mechanical stimulation of the mucosal epithelium, ATP mediates 5-HT release from EC cells in the ileum, but not the colon. Mucosal 5-HT signaling following mechanical stimulation is varied in different regions of the intestinal tract.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, UK.
authors.forename: B A
authors.initials: BA
authors.lastname: Patel
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D004759:Enterochromaffin Cells / Q000378:metabolism*; D006168:Guinea Pigs; D007082:Ileum / Q000166:cytology / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D010812:Physical Stimulation; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin; D000255:Adenosine Triphosphate
keywords: adenosine triphosphate; colon; enterochromaffin cell; ileum; mechanosensory; purinergic; serotonin