Stimulation of acid formation in permeable gastric glands by valinomycin.
Isolated gastric glands made permeable with digitonin treatment were employed to study the ionic requirements of acid formation. Acid formation was monitored by the accumulation of a novel weak base probe, [14C]benzylamine. ATP-dependent acid formation was found to require K+ in a concentration-dependent manner, with an apparent K0.5 = 7 mM. The anion dependence of acid formation gave a selectivity sequence of Cl = I greater than Br greater than NO3 greater than SO4 = isethionate, with isethionate being approximately 50% as effective as Cl. The dependence of acid formation on [Cl] gave an apparent K0.5 = 6 mM. Addition of the K+ ionophore, valinomycin, to resting glands (cimetidine pretreatment) resulted in a two- to threefold increase in ATP-dependent acid formation. In contrast, stimulated (forskolin pretreated) glands showed a greater accumulation of benzylamine with ATP but significantly less valinomycin stimulation. The valinomycin stimulation required both K+ and Cl- and was inhibited by omeprazole and Sch 28080. The results are interpreted to indicate that major events in the transition from a resting to a stimulated state include changes in both K+ and anion permeability of the secretory membrane of parietal cells.
Department of Physiology, Emory University, Atlanta, Georgia 30322.
S J
SJ
Hersey
L
L
Steiner
D000818:Animals; D000838:Anions; D001596:Benzylamines / Q000493:pharmacokinetics; D002414:Cations, Monovalent; D002463:Cell Membrane Permeability; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D011188:Potassium / Q000494:pharmacology; D011817:Rabbits; D012016:Reference Values; D014634:Valinomycin / Q000494:pharmacology*
D000838:Anions; D001596:Benzylamines; D002414:Cations, Monovalent; D014634:Valinomycin; C030796:benzylamine; D011188:Potassium