Measurement of the rate of flow of pancreatic secretion in the anesthetized chicken

Trypsin inhibitor and the nutritional value of soya beans

1. One reason, based on indirect evidence, advanced in explanation of the low nutritional value of raw soya bean (RS) is that it stimulates the pancreas to secrete massive amounts of protein which are ultimately lost in the faeces. This theory has been investigated directly.

2. The expected outpouring of pancreatic protein did not occur when the secretion of enzymes and protein in pancreatic juice from chickens and rats given successively heated soya bean (HS) and RS diets was measured directly.

3. It is suggested that RS, acting upon intestinal proteins, forms trypsin inhibitor-protein complexes which, in spite of adequate proteolytic activity, escape digestion and are lost with the faeces, thus decreasing the nutritional value of the diet.

Influence of avian pancreatic polypeptide on pancreatic and biliary secretion in laying hens

White Leghorn hens, 14 to 29 wk of age, were surgically prepared with cannulae for collecting secretions from the cystic duct and the duct draining the ventral pancreatic lobe and for infusing the jugular vein with avian pancreatic polypeptide (aPP) or saline. A plasma infusion rate that produced a plasma level of 15 ng of aPP/mL was used. A comparison of values obtained during saline infusion with those obtained during aPP infusion indicated that pancreatic and biliary secretory volumes and pancreatic total protein concentration were significantly depressed by aPP. The pH of pancreatic and biliary secretions were not significantly affected by aPP. Because aPP also depresses gastric secretion and motility in hens, it is proposed that its physiological role may be to oppose or modulate the actions of other, stimulatory gastrointestinal hormones.

The influence of cholecystokinin, vasoactive intestinal peptide and secretin on pancreatic and biliary secretion in laying hens

White Leghorn hens, 14-29 weeks old, were surgically fitted with cannulas for collecting pancreatic and biliary secretions, and a jugular cannula for continuous infusion of either cholecystokinin (CCK), vasoactive intestinal peptide (VIP), or secretin. As compared to secretory levels during saline infusion, CCK significantly stimulated biliary flow and biliverdin concentration in bile; VIP significantly depressed biliverdin concentration but enhanced bicarbonate secretion in both pancreatic and biliary secretions, and also increased total pancreatic flow. Secretin depressed biliary flow and increased pancreatic bicarbonate release. The principal hormonal regulator of biliary secretion appears to be CCK, and that of pancreatic secretion to be VIP.

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.