Gastric H+ and HCO3- secretion in response to sham feeding in humans.
Sham feeding (SF) was used to evaluate the effect of physiological vagal stimulation on gastric acid (H+) and bicarbonate (HCO3-) secretion in humans, as well as on parietal and nonparietal volume secretion. A recently validated method, derived from a two-component model of gastric secretion, was employed. SF increased both H+ secretion from parietal cells (P less than 0.001) and HCO3- secretion from nonparietal cells (P less than 0.01), although the H+ response was greater and more prolonged. Atropine significantly inhibited not only H+ secretion but also HCO3- and nonparietal volume secretion. Peak H+ secretion during SF averaged approximately 27 mmol/h, whereas peak HCO3- secretion averaged approximately 6 mmol/h. When H+ secretion was already maximally stimulated by an intravenous pentagastrin infusion, SF actually reduced gastric juice acidity and osmolality due to neutralization of H+ by HCO3- and to dilution of H+ by nonparietal secretions. These studies therefore indicate that vagal stimulation induced by SF increases both H+ and HCO3- secretion in humans and that this process is cholinergically dependent.
D000328:Adult; D001285:Atropine / Q000494:pharmacology; D001639:Bicarbonates / Q000378:metabolism*; D004435:Eating; D005260:Female; D005750:Gastric Juice / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D006801:Humans; D006859:Hydrogen / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007275:Injections, Intravenous; D008297:Male; D009994:Osmolar Concentration; D010295:Parietal Cells, Gastric / Q000378:metabolism; D010418:Pentagastrin / Q000494:pharmacology; D013268:Stimulation, Chemical; D014630:Vagus Nerve / Q000502:physiology
D001639:Bicarbonates; D001285:Atropine; D006859:Hydrogen; D010418:Pentagastrin