Cation transport in vesicles from secreting rabbit stomach.
K+ gradient-dependent rubidium flux in vesicles obtained from stimulated rabbit stomach distinguishes two cation pathways. Selective inhibition by vanadate and the (1,2-alpha)-imidazopyridine, SCH 28080 identifies one pathway as H,K-ATPase-mediated passive cation exchange. A second pathway, additive to the first, is inhibited by the protonophore, tetrachlorosalicylanilide and is identified as a K+ conductance pathway present in these vesicles. The conductance was limited to vesicle populations obtained from the stimulated rabbit gastric mucosa and was distributed into both a light microsomal fraction and a heavier membrane fraction. 86Rb+ transport through the cation conductance exhibited a trans-stimulated cation selectivity sequence of K+ greater than Rb+ = Cs+ much greater than Li+. Potential sensitive flux was inhibited by the cyanine dye 3,3'-dipropyl-2,2'-thiodicarbo cyanine iodide, Ba2+, quinine, and the guanidinium compound 1,8-bis-guanidinium-n-octane. The presence of the conductance was correlated with K+-dependent H+ transport which did not require prolonged equilibration in K+ medium for activation. A role for the stimulus-dependent K+ conductance in gastric acid secretion could be its provision of a pathway for net K+ movement to the luminal site of the H,K-ATPase.
Gunther
R D
RD
Center for Ulcer Research and Education, Veterans Administration Medical Center, Wadsworth Division, Los Angeles, California 90073.
Bassilian
S
S
Rabon
E C
EC
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D000897:Anti-Ulcer Agents / Q000494:pharmacology; D002458:Cell Fractionation; D002499:Centrifugation, Density Gradient; D003594:Cytoplasmic Granules / Q000201:enzymology* / Q000648:ultrastructure; D005753:Gastric Mucosa / Q000201:enzymology* / Q000378:metabolism; D017506:H(+)-K(+)-Exchanging ATPase; D007093:Imidazoles / Q000494:pharmacology; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology; D011817:Rabbits; D012413:Rubidium / Q000378:metabolism; D014634:Valinomycin / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D000897:Anti-Ulcer Agents; D007093:Imidazoles; C035235:Sch 28080; D014634:Valinomycin; D014638:Vanadates; D000251:Adenosine Triphosphatases; D017506:H(+)-K(+)-Exchanging ATPase; D012413:Rubidium