Histamine delays gastric emptying of solid food in man through histamine, receptors

The authors have shown that histamine (H) contracts the cat pylorus and duodenum through H/sub 1/ receptor mechanisms. The authors investigated the effect of H infusion on gastric emptying (GE) and the role of H/sub 1/ and H/sub 2/ receptor blockade in healthy volunteers. Radionuclide GE studies were performed using chicken liver labeled in vivo with /sup 99m/Technetium-sulfur colloid as a marker of solid food. Study days were as follows: a baseline GE study (Day 1); H infused continuously IV at a rate of 40 μg/kg/hr during the GE study (Day 2); an IV bolus of 50 mg of diphenhydramine (Day 3), or 300 mg cimetidine (Day 4) given just prior to the continuous infusion of H; a final day when cimetidine was given alone (Day 5). GE was monitored for 2 hours on each day. The results of days 1, 2 and 3 are summarized below (+p<0.05 vs baseline or Day 1). Pretreatment with cimetidine (Day 4) augmented the delay in GE induced by H infusion, while cimetidine without H (Day 5) had no effect on GE. The authors conclude that: 1) H given at a dose which elicits maximal acid secretory response in man significantly delays GE; and 2) H/sub 1/ receptor blockade but not H/sub 2/ blockade prevented this effect. Histamine may play a modulatory role in human gastric emptying through an H/sub 1/ receptor mechanism