title: Radiation decreases murine small intestinal HCO3- secretion.
abstract: OBJECTIVE
  While secretagogue-induced diarrhea is rich in chloride (Cl(-)) and bicarbonate (HCO(3) (-)) anions, little is known about diarrhea or its anionic composition following irradiation. We performed studies to characterize the differences between cyclic adenosine monophosphate (cAMP)-stimulated anion secretions in irradiated and non-irradiated mice.
  
  
  METHODS
  HCO(3) (-) secretion was examined in basal, cAMP-stimulated, and irradiated jejunal tissues from BALB/c (Bagg albino) mice. The abdomens of the mice were γ-irradiated using a caesium-137 source.
  
  
  RESULTS
  Ussing-chamber experiments performed in an HCO(3)(-)-containing, Cl(-)-free solution on the bath side showed inhibition of HCO(3)(-) in irradiated mice. Non-irradiated mice exhibited bumetanide-sensitive and insensitive current, while irradiated mice displayed bumetanide-sensitive current. pH-stat experiments showed inhibition of basal and cAMP-stimulated HCO(3)(-) secretions in irradiated mice. Immunohistochemistry and Western blot analysis displayed a sodium-bicarbonate cotransporter expression in the villus and not the crypt of non-irradiated mice, while its expression and protein levels decreased in irradiated mice.
  
  
  CONCLUSIONS
  Anion secretions in irradiated mice, being primarily Cl(-) and minimally HCO(3)(-), differ from that of secretagogue-induced anion secretions. Understanding anion loss will help us correct electrolyte imbalances, while reduced HCO(3)(-) secretion in the upper-gastrointestinal tract might also have implications for irradiation-induced nausea and vomiting.
authors.affiliation: Vascular Medicine Research, Brigham and Women's Hospital, Harvard Medical School, Cambridge, Massachusetts, USA. K. Zhang
authors.forename: Kunzhong
authors.initials: K
authors.lastname: Zhang
authors.forename: Liangjie
authors.initials: L
authors.lastname: Yin
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: Mark Daniel
authors.initials: MD
authors.lastname: Parker
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Binder
authors.forename: Peter
authors.initials: P
authors.lastname: Salzman
authors.forename: Lurong
authors.initials: L
authors.lastname: Zhang
authors.forename: Paul
authors.initials: P
authors.lastname: Okunieff
authors.forename: Sadasivan
authors.initials: S
authors.lastname: Vidyasagar
mesh_terms: D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D004307:Dose-Response Relationship, Radiation; D007421:Intestine, Small / Q000000981:diagnostic imaging* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D011829:Radiation Dosage; D011859:Radiography; D014916:Whole-Body Irradiation
chemical_list: D001639:Bicarbonates