Effect of loxiglumide (CR-1505) on bombesin- and meal-stimulated plasma cholecystokinin in man.

Cholecystokinin (CCK)-receptor antagonists have been reported to inhibit the effects of the hormone on the gastrointestinal tract. Their effect on plasma CCK levels in man has not been described. The present study in 5 normal subjects demonstrated that i.v. infusion of the potent, specific CCK-receptor antagonist loxiglumide (CR 1505) significantly augmented plasma CCK levels during infusion of bombesin (402 pM per 30 min) and after administration of a meal (1390 pM per 300 min) when compared to the bombesin- (192 pM per 30 min) and meal- (886 pM per 300 min) stimulated CCK responses during infusion of saline. The basal plasma CCK during saline infusion (0.1 pM per 40 min) was not significantly influenced by CR 1505 (-1.8 pM per 40 min). Thus, both enteral (meal) and parenteral (bombesin) stimulation of CCK secretion are augmented by CCK-receptor blockade.