title: Stimulation of oxyntic cell triggers K+ and Cl- conductances in apical H+-K+-ATPase membrane.
abstract: Vesicles isolated from the apical membrane of stimulated oxyntic cells [stimulation-associated (SA) vesicles] are highly permeable to KCl. The KCl flux is coupled to an electroneutral ATP-driven H+-K+ exchange (the H+-K+-ATPase) to produce net intravesicular HCl accumulation. In the past, we observed that rates of KCl transport were not accelerated by valinomycin and that dissipation of preformed H+ gradients in the presence of a protonophore (carbonyl cyanide, m-chlorophenylhydrazone, 10 microM) required the simultaneous presence of valinomycin. Consequently the fast KCl transport was attributed to an electroneutral cotransport system. Now we have been able to elicit fast H+ gradient dissipation in the absence of valinomycin by using the protonophore tetrachlorosalicylanilide. Experiments carried out in the absence of Cl- demonstrated the existence of a specific high-conductance pathway for K+. Experiments in K+-free medium demonstrated the existence of a high Cl- conductance. Parallel experiments in the equivalent H+-K+-ATPase-rich vesicles from nonsecreting oxyntic cells showed very little K+ and Cl- conductivity, suggesting that the appearance of large ionic conductance in the membrane is associated with the stimulation of the cell.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D004553:Electric Conductivity / Q000187:drug effects; D005744:Gastric Acid / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000201:enzymology / Q000502:physiology*; D017506:H(+)-K(+)-Exchanging ATPase; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008861:Microsomes / Q000502:physiology; D011189:Potassium Chloride / Q000378:metabolism*; D011817:Rabbits; D012458:Salicylanilides / Q000494:pharmacology
chemical_list: D012458:Salicylanilides; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D011189:Potassium Chloride; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase; C003390:3,3',4',5-tetrachlorosalicylanilide