Relationship between hydrogen ion concentration and flow of gastric juice during inhibition of gastric secretion in the cat.

1. The normal relationship between the [H+] and rate of flow of gastric juice was determined in conscious cats prepared with cannulated gastric fistulae. Gastric secretion was monitored during stimulation with pentagastrin, insulin and histamine. 2. [H+] rose asymptotically with the flow of gastric juice. This relationship was quantified by applying the data to the integrated form of the Fick equation for diffusion, a graphical plot of log [H+] vs. 1/flow. The calculated relationships were similar for gastric secretion stimulated by pentagastrin, insulin and histamine, and were used to define the normal relationship between gastric [H+] and flow. 3. Significant inhibition of pentagastrin-stimulated gastric secretion with the histamine H2-receptor antagonists, metiamide and cimetidine, atropine or somatostatin did not alter the normal relationship between [H+] and flow; the [H+] observed fell within the normal range observed at that flow rate in the presence of pentagastrin alone. Similarly, inhibition of insulin-stimulated secretion with metiamide, did not alter the normal relationship between [H+] and flow of gastric juice. 4. These data provide evidence that histamine H2-receptor antagonists, atropine and somatostatin all act to reduce the primary rate of acid secretion and do not influence the [H+] per se, either by interfering with back-diffusion of H+, or by changing the proportions of a non-parietal component of gastric secretion added to the parietal H+ component.