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Possible mechanism for the inhibition of gastric (H+ + K+)-adenosine triphosphatase by the proton pump inhibitor AG-1749

Journal Article · · J. Pharmacol. Exp. Ther.; (United States)
OSTI ID:6327088
Mechanisms related to the inhibition of (H+ + K+)-adenosine triphosphatase (ATPase) by 2-(((3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridyl)methyl) sulfinyl)-1H-benzimidazole (AG-1749) were studied using canine gastric microsomes. AG-1749 (1-100 microM) inhibited the K+-stimulated ATP hydrolysis and vesicular accumulation of H+. AG-1749 bound to the microsomes concentration-dependently and decreased the number of free SH groups; the binding correlating with the enzyme inhibition. Both the binding and inhibition were antagonized by dithiothreitol. N-ethylmaleimide inhibited the (H+ + K+)-ATPase and decreased the binding of (/sup 14/C)AG-1749 to the microsomes. The inhibitory effect of AG-1749 gradually increased with incubation time, and was enhanced by lowering the pH. AG-2000 and AG-1812, acid-induced rearrangement products of AG-1749, inhibited (H+ + K+)-ATPase potently, rapidly and independently of pH; the inhibition was antagonized by dithiothreitol. We propose that AG-1749 is transformed into its active forms within the acidic compartment of the parietal cells and that the active compounds inhibit (H+ + K+)-ATPase activity by reacting with the SH groups of the enzyme.
Research Organization:
Takeda Chemical Industries, Ltd., Osaka (Japan)
OSTI ID:
6327088
Journal Information:
J. Pharmacol. Exp. Ther.; (United States), Journal Name: J. Pharmacol. Exp. Ther.; (United States) Vol. 248:2; ISSN JPETA
Country of Publication:
United States
Language:
English