Comparison of the actions of porcine secretin and extracts of chicken duodenum on pancreatic exocrine secretion in the cat and turkey.

1. Extracts were prepared of chicken duodenum and their actions on pancreatic secretion in urethane anasthetized turkeys and in conscious cats were compared with those of pure natural porcine secretin. 2. The chicken extracts and porcine secretin stimulated dose-dependent increases in the rate of flow, but not the rate of protein secretion, from the pancreas in cats and turkeys. 3. Porcine cholecystokinin stimulated both the rate of flow and the rate of protein secretion from the pancrease in turkeys. 4. The doses of chicken extract required to evoke half maximal rates of flow of pancreatic juice were similar in the turkey (0-55 mg/kg) and in the cat (0-72 mg/kg). The highest concentration of bicarbonate recorded in the turkey responses was 30 m-equiv/l. compared with 112 m-equiv/l. in the cat. 5. The dose of porcine secretin required for half maximal rate of flow in the bird (5-9 mug/kg) was 180 times higher than in the mammal (0-33 mug/kg). In the cat the duration of responses to porcine secretin was significantly greater than to the chicken extract. 6. It is concluded that in birds there is a factor with biological properties similar but not identical to those of porcine secretin, and that this factor may regulate pancreatic secretion by a mechanism resembling the secretin mechanism in mammals.