Metabolic and membrane aspects of gastric H+ transport.
Metabolic properties of dog gastric mucosa, investigated by substrate level measurements, implicate the Krebs cycle as the major energy-yielding metabolic pathway but are equivocal in terms of an ATP-based H+ secretion. Purification of gastric membranes by centrifugation and free flow electrophoresis results in a class of membrane vesicles enriched in K+-ATPase and capable of ATP-energized H+ uptake. Immunohistochemistry shows these to be derived from the parietal cell. H+ uptake by the vesicles is accompanied by K+ efflux, and movement of either ion is not potential-coupled. The simplest interpretation of these transport studies is uptake of KCl by the vesicles by passive diffusion followed by active H+:K+ exchange. In some respects, however, this model fails to conform to the expectations from in vitro studies. It may be, therefore, that another pump (i.e., redox) or another membrane component (i.e., Cl- conductance) is lost during purification. The properties of the vesicles are such, however, as to establish their role in H+ secretion by the stomach.
D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D002462:Cell Membrane / Q000032:analysis / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D002952:Citric Acid Cycle; D004285:Dogs; D005750:Gastric Juice / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D006859:Hydrogen / Q000378:metabolism*; D066298:In Vitro Techniques; D050356:Lipid Metabolism; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010725:Phosphocreatine / Q000378:metabolism; D011188:Potassium / Q000378:metabolism
D002712:Chlorides; D010725:Phosphocreatine; D009243:NAD; D000244:Adenosine Diphosphate; D006859:Hydrogen; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D005947:Glucose; D011188:Potassium