Stimulation of duodenal epithelial HCO3- transport in the guinea pig and cat by luminal prostaglandin E2.
Segments of guinea pig or cat duodenum distal to the Brunner gland containing area and devoid of bile or pancreatic secretions were cannulated in situ. The unbuffered luminal solution was gassed with 100% O2 or N2 and HCO3- transport titrated at pH 7.40 or 8.00 with solutions containing HCl. Cat duodenum transported HCO3- at a greater rate (approximately 17 mueq, cm-1, h-1) than did jejunum in the same animals (approximately 5 mueq, cm-1, h-1) and also developed a greater transmucosal electrical potential difference. Luminal application of PGE2 (1-12 micrometers) in cat duodenum increased HCO3- transport and the potential difference. HCO3- transport by guinea pig duodenum (approximately 27 mueq cm-1, h-1) was increased by luminal PGE2 only in animals where transport had been inhibited by pretreatment with aspirin (30 mg/kg intravenously). Exposure of the cat duodenal lumen to HCl (1-25 mM, 5 min) stimulated HCO3- transport and continuous exposure of duodenum in the guinea pig to acid discharged from the stomach may increase endogenous prostaglandin concentrations, resulting in an apparent lack of effect of exogenous prostaglandins. The present results and previous similar findings in amphibians in vitro suggest that surface epithelial transport of HCO3- protects duodenal mucosa against acid.
D000818:Animals; D001241:Aspirin / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism*; D002415:Cats; D015232:Dinoprostone; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D007408:Intestinal Absorption / Q000187:drug effects*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D011458:Prostaglandins E / Q000494:pharmacology*
D001639:Bicarbonates; D011458:Prostaglandins E; D015232:Dinoprostone; D001241:Aspirin