Oleic acid as an inhibitor of gastric H+, K(+)-ATPase

A study was made of the effects of oleic acid on gastric H+, K(+)-ATPase. Oleic acid inhibited both H+, K(+)-ATPase and K(+)-pNPPase from pig gastric mucosa. The concentrations for 50% inhibition were 7.8 x 10(-6) M and 5.0 x 10(-6) M respectively. Oleic acid also inhibited Na+, K(+)-ATPase with an IC50 value of 1.2 x 10(-5) M. Double reciprocal plots demonstrated the inhibition of gastric H+, K(+)-ATPase by oleic acid to be noncompetitive with respect to K+ and competitive with respect to ATP. A proton transport experiment also showed oleic acid to inhibit H+, K(+)-ATPase mediated acid secretion. Oleic acid may thus possibly be a potent inhibitor of gastric H+, K(+)-ATPase and that the inhibition of H+, K(+)-ATPase may be responsible for the antisecretory effect of oleic acid.