Different effects of CCK antagonists on gastric-acid response to CCK and pentagastrin

The role of CCK receptor subtypes in peptide-stimulated acid secretion was assessed in six unanesthetized rats. The CCK-stimulated acid secretion was not blocked by L-365,260, a CCKB/gastrin receptor antagonist, and was significantly increased by devazepide, a CCKA receptor antagonist, given alone or together with L-365,260. L-365,260, but not devazepide, blocked pentagastrin-stimulated acid secretion, and, when given together, devazepide abolished the effect of L-365,260. We conclude: 1) pentagastrin stimulates acid secretion through a gastrin-type receptor, but CCK may not, and 2) pentagastrin and CCK can stimulate acid secretion despite simultaneous blockade of CCKB/gastrin and CCKA receptors.