title: Luminal oxidants selectively modulate electrogenic ion transport in rat colon.
abstract: OBJECTIVE
  To investigate the effects of luminal exposure to H2O(2) and two related thiol oxidizing agents on basal and stimulated chloride secretion in native colon using electrophysiological and pharmacological approaches.
  
  
  METHODS
  Unstripped rat distal colon segments were mounted in Ussing chambers. Potential difference, calculated resistance and short-circuit current across unstripped colon segments were monitored with a dual voltage/current clamp. Paracellular permeability was assessed by measuring the mucosa-to-serosa flux of a fluorescent probe (FITC).
  
  
  RESULTS
  Luminal exposure to hydrogen peroxide transitorily stimulated chloride secretion without altering barrier function. This stimulatory effect could be blocked by basolateral atropine but not indomethacin. The cysteine and methionine oxidizing compounds, phenylarsine oxide and chloramine T respectively, mimicked the effect of H2O(2), except for a drop in transcolonic resistance after 30 min. In contrast to the observed stimulatory effect on basal secretion, cAMP-stimulated electrogenic ion transport was blunted by luminal H2O(2). However, the Ca(2+)-activated response remained unchanged.
  
  
  CONCLUSIONS
  H2O(2) may be an important selective modulator of intestinal ion and water secretion in certain pathologic conditions such as inflammation or ischemia-reperfusion by multiple mechanisms.
authors.affiliation: Servicio de Cirugia I (3(a) N), Hospital Clinico San Carlos, Universidad Complutense de Madrid, Madrid 28040, Spain. jmayol@eresmas.net
authors.forename: Julio M
authors.initials: JM
authors.lastname: Mayol
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Adame-Navarrete
authors.forename: Pilar
authors.initials: P
authors.lastname: Alarma-Estrany
authors.forename: Elena
authors.initials: E
authors.lastname: Molina-Roldan
authors.forename: Fernando
authors.initials: F
authors.lastname: Huete-Toral
authors.forename: Jesus A
authors.initials: JA
authors.lastname: Fernandez-Represa
mesh_terms: D000818:Animals; D001152:Arsenicals / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002700:Chloramines / Q000494:pharmacology; D002712:Chlorides / Q000493:pharmacokinetics; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D004594:Electrophysiology; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007213:Indomethacin / Q000494:pharmacology; D017136:Ion Transport / Q000187:drug effects*; D008297:Male; D016877:Oxidants / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D014105:Tosyl Compounds / Q000494:pharmacology; D014867:Water / Q000502:physiology
chemical_list: D001152:Arsenicals; D002700:Chloramines; D002712:Chlorides; D016877:Oxidants; D014105:Tosyl Compounds; C016300:chloramine-T; D014867:Water; C029341:oxophenylarsine; D001285:Atropine; D006861:Hydrogen Peroxide; D002118:Calcium; D007213:Indomethacin