The Gastric “Mucus-Bicarbonate” Barrier: Effect of Luminal Acid on HCO3- Transport by Amphibian Fundic Mucosa In Vitro
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Transport of HCO- 3 by surface epithelial cells has been demonstrated in amphibian isolated gastric mucosa (Flemstrom, 1977) and in mammalian stomach in vivo (Garner and Flemström, 1978). These studies together with work on surface mucus gel have led to the proposal that the two secretions provide a first line of defense against intraluminal H+ ions (Allen and Garner, 1980). Although the stimulatory pathways controlling acid secretion and HCO- 3 transport are different, titratable alkalinity of fluid perfusing the canine Heidenhain pouch increased following instillation of HC1 into the gastric remnant (Garner and Hurst, 1980). Thus regulation of gastric HCO- 3 output by intraluminal acid may involve a humoral mechanism. The present study was designed to investigate the effect of luminal acidification on alkaline secretion by the isolated mucosa.
KeywordsGastric Remnant Surface Epithelial Cell Bicarbonate Secretion Fundic Mucosa Luminal Acidification
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