Pentagastrin-Stimulated gastric acid secretion: Does desensitization exist?

The existence of tachyphylaxis to pentagastrin-stimulated gastric acid secretion in humans is controversial. To study this, we determined gastric acid output in 19 duodenal ulcer patients following the administration of two successive intramuscular injections of pentagastrin (6 μg/kg body weight). In 18 of 19 patients, the maximal acid output decreased by 33.73 ± 3.25% (mean ± SE) following the second pentagastrin administration when compared with the maximal acid output following the first injection. This study indicates the existence of tolerance to pentagastrin-induced gastric acid secretion in humans, which may be due to a receptor-mediated phenomenon of ”down-regulation.”