title: Role of carbonic anhydrase in basal and stimulated bicarbonate secretion by the guinea pig duodenum.
abstract: The role of carbonic anhydrase in the process of proximal duodenal mucosal bicarbonate secretion was investigated in the guinea pig. In a series of experiments in vivo, the duodenum was perfused with 24 mmol/liter NaHCO3 solution (+ NaCl for isotonicity) to ensure that active duodenal HCO3- secretion against a concentration gradient was measured. Acetazolamide (80 mg/kg) was infused intravenously to examine the role of carbonic anhydrase on basal and agonist-stimulated HCO3- secretion. Acetazolamide abolished basal HCO3- secretion and significantly decreased HCO3- secretion after stimulation with dibutyryl 5'-cyclic adenosine monophosphate (dBcAMP, 10(-5) mol/kg), dibutyryl 5'-cyclic guanosine monophosphate (dBcGMP, 10(-5) mol/kg), prostaglandin E2 (PGE2, 10(-6) mol/kg), PGF2 alpha (10(-6) mol/kg), tetradecanoyl-phorbol-acetate (TPA, 10(-7) mol/kg), glucagon (10(-7) mol/kg), vasoactive intestinal polypeptide (VIP, 10(-8) mol/kg), and carbachol (10(-8) mol/kg). Utilizing a fluorescence technique, we could detect the enzyme carbonic anhydrase in equal amounts in villous and crypt cells of the proximal duodenal epithelium; no activity was demonstrated in tissues pretreated with acetazolamide. In conclusion, carbonic anhydrase is required for both basal and stimulated duodenal HCO3- secretion.
authors.affiliation: Gastroenterology Institute, Soroka Medical Center, Beer Sheva, Israel.
authors.forename: R
authors.initials: R
authors.lastname: Muallem
authors.forename: R
authors.initials: R
authors.lastname: Reimer
authors.forename: H S
authors.initials: HS
authors.lastname: Odes
authors.forename: M
authors.initials: M
authors.lastname: Schwenk
authors.forename: W
authors.initials: W
authors.lastname: Beil
authors.forename: K F
authors.initials: KF
authors.lastname: Sewing
mesh_terms: D000086:Acetazolamide / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D002256:Carbonic Anhydrases / Q000502:physiology*; D003995:Dibutyryl Cyclic GMP / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D004386:Duodenum / Q000201:enzymology / Q000378:metabolism*; D005934:Glucagon / Q000494:pharmacology; D006168:Guinea Pigs; D008297:Male; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
chemical_list: D001639:Bicarbonates; D003995:Dibutyryl Cyclic GMP; D014660:Vasoactive Intestinal Peptide; D003994:Bucladesine; D002217:Carbachol; D005934:Glucagon; D002256:Carbonic Anhydrases; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D000086:Acetazolamide