The action of caerulein on pancreatic and biliary secretions of the chicken

Caerulein, by intravenous infusion, had a strong stimulating action on the chicken's pancreatic secretion. Threshold rates were 0.1–0.25 ng/kg/min. Subcutaneous injection proved ineffective up to 5 mug/kg; by rapid intravenous injection the action was manifest only with 50 ng/kg. Caerulein increased output of fluid, bicarbonate and enzymes, greatly enhancing the enzyme concentration. Atropine inhibited the effect of caerulein on enzyme concentration only. Porcine secretin had no effect on the chicken's pancreatic secretion. Flow of hepatic bile and the output of solid biliary components were also stimulated by caerulein. The threshold doses were: 10 ng/kg by rapid intravenous injection, and 0.5 ng/kg/min by intravenous infusion. These actions were not inhibited by atropine. Caerulein hastened plasma clearance and biliary excretion of BSP. Furthermore, it increased output of cystic bile by stimulating gall bladder motility. Tachyphylaxis to effects of caerulein on pancreastic or biliary secretions was not seen. Porcine secretin reduced the flow of hepatic bile by intravenous infusion. The mechanism of action of caerulein is discussed.