Influence of the stimulation state of the parietal cells on the inhibitory effect of omeprazole on gastric acid secretion in dogs.

The relationship between the stimulation state of the parietal cells and the gastric antisecretory properties of omeprazole has been evaluated in dogs with gastric fistulas maximally stimulated with pentagastrin. Intravenous administration of omeprazole (5 mumol/kg) 4 h before the start of stimulation with pentagastrin inhibited the acid response by 71%. This inhibition was prevented when omeprazole was given during an infusion of somatostatin at a dose that completely inhibited acid secretion. When given 18 h before stimulation with pentagastrin, omeprazole inhibited the acid response by 50%. This inhibitory effect was almost completely suppressed when omeprazole was administered during an infusion of somatostatin or after the administration of cimetidine, and was increased when omeprazole was given during an infusion of pentagastrin. These data indicate that the inhibitory effect of omeprazole given by rapid intravenous injection is related to the activity of the parietal cells at the moment of administration of the drug. They suggest that, in the intact animal as well as in the isolated gastric glands, the uptake of omeprazole by the parietal cells is related to the stimulation state of these cells.