Betazole-induced GIP secretion is not mediated by gastric HCl

Betazole, a pyrazole analogue of histamine, as well as pentagastrin and HCl stimulate GIP secretion. We have asked the question as to whether betazole acts directly or via the production of HCl. Eight normal subjects and 4 patients with achlorhydria secondary to pernicious anemia were given betazole (0.5 mg/kg) by IM injection. Another six normal subjects were also given betazole but this was preceded by 200 mgs. of the H2 receptor blocker cimetidine given IV 60 mins. previously and a slow infusion of 200 mg. cimetidine given over the next 4 hr. Our results have shown that the GIP response to betazole is maintained in achlorhydric subjects as well as during H2 blockade. The results suggest that betazole and therefore histamine may stimulate GIP directly and not necessarily via the mediation of HCl.