title: Cigarette smoking inhibits acid-stimulated duodenal mucosal bicarbonate secretion.
abstract: OBJECTIVE
  To determine the effect of cigarette smoking on proximal duodenal mucosal bicarbonate secretion, an important defense mechanism against acid and peptic damage.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Clinical research laboratory in a university hospital.
  
  
  METHODS
  Thirteen healthy adults (7 smokers and 6 nonsmokers) who had no history of peptic ulcer disease.
  
  
  METHODS
  Participants smoked (1 cigarette/15 min during a period of 1 hour, smokers only) or sham smoked (puffing on an unlit cigarette) during duodenal perfusion with either saline, hydrochloric acid, or prostaglandin E2 (PGE2).
  
  
  METHODS
  Collection of proximal duodenal secretions using a modified duodenal tube with occluding balloons and quantitation of duodenal mucosal bicarbonate secretion.
  
  
  RESULTS
  During sham smoking both smokers and nonsmokers had comparable basal as well as H(+)-stimulated and PGE2-stimulated duodenal mucosal bicarbonate secretion. Compared with sham smoking, smoking did not significantly alter basal bicarbonate secretion (201 mumol/cm per hour [95% CI, 152 to 250 mumol/cm per hour] compared with 178 mumol/cm per hour [CI, 134 to 222 mumol/cm per hour], respectively). However, compared with sham smoking, smoking markedly reduced (P < 0.01) the increase in duodenal bicarbonate secretion in response to luminal acidification by approximately 80% (from 242 mumol/cm per hour [CI, 41 to 443 mumol/cm per hour] to 53 mumol/cm per hour [CI, -107 to 197 mumol/cm per hour]); a decrease was observed in each participant. In contrast, smoking had no significant effect on the response to luminal PGE2.
  
  
  CONCLUSIONS
  Cigarette smoking markedly inhibited acid-stimulated human duodenal mucosal bicarbonate secretion. This adverse effect of smoking may, at least in part, explain the role of cigarette smoking in the pathogenesis and natural history of duodenal ulcer disease.
authors.affiliation: San Diego Medical Center, University of California.
authors.forename: M A
authors.initials: MA
authors.lastname: Ainsworth
authors.forename: D L
authors.initials: DL
authors.lastname: Hogan
authors.forename: M A
authors.initials: MA
authors.lastname: Koss
authors.forename: J I
authors.initials: JI
authors.lastname: Isenberg
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001639:Bicarbonates / Q000378:metabolism*; D015232:Dinoprostone / Q000502:physiology; D004381:Duodenal Ulcer / Q000209:etiology; D004386:Duodenum / Q000378:metabolism*; D005260:Female; D005744:Gastric Acid / Q000502:physiology; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology*
chemical_list: D001639:Bicarbonates; D015232:Dinoprostone