Action of caerulein on gastric emptying of the conscious rat

Caerulein was shown to delay gastric emptying in conscious rats in a dose-dependent fashion. The threshold dose was about 0.05 mug/kg by the intraperitoneal route. Maximum effect was obtained with 5 mug/kg. Neutralization of acidity or reduction of gastric juice by mean of NaHCO3 or cimetidine, respectively, did not modify the effect of the peptide. Chlorpheniramine was similarly ineffective. The effect of caerulein on gastric emptying was most probably connected with a strong contraction of the gastroduodenal junction previously observed in different experimental conditions and was not affected by H1- or H2-histamine antagonists. The C-terminal heptapeptide of cholecystokinin behaved quite similarly to caerulein. The present study emphasizes the close parallelism between results obtained in the in situ stomach preparation of anaesthetized rats and gastric emptying in conscious animals.