The pentagastrin-induced gastric acid response in humans.

The pentagastrin-induced acid response, alone and versus different doses of cimetidine, was studied in humans. The inhibitory effect of the histamine H2-receptor antagonist cimetidine could only in part be counteracted by increasing doses of pentagastrin. The maximal gastric acid response was significantly decreased by cimetidine, and the ED50 values for pentagastrin showed a minor but still statistically significant increase, indicating both a competitive and a non-competitive inhibition by cimetidine of pentagastrin-induced gastric acid secretion. The pA2 characterization of the receptor mediating the pentagastrin-induced gastric acid response gave a value of 6.2, compared with the pA2 value of the human H2 receptor of 6.1. This suggests that the pentagastrin-induced gastric acid response in humans is mediated via the histamine H2-receptor.