Similar modes of action of calcitonin and glucagon in inhibiting pancreatic enzyme secretion in man

Studies on the effect of glucagon on human pancreatic secretion by analysis of endoscopically obtained pure pancreatic juice

The effect of glucagon on human exocrine pancreatic secretion was evaluated in ten patients by analysis of pure pancreatic juice. Pancreatic juice was obtained by endoscopic cannulation of the pancreatic duct at 2-min intervals during constant intravenous infusion of secretin (1 U per kg of body weight per hr) plus caerulein (0.04 micrograms per kg of body weight per hr). Since steady secretion was established 20 minutes after the start of juice collection, a further five 2-min fractions were collected as controls, then constant intravenous infusion of glucagon (15 micrograms per kg of body weight per hr) was commenced. Pancreatic juice was collected for a further 20 minutes. The control fractions and post-glucagon fractions were compared in each patient using Student's test. Glucagon depressed secretin-caerulein-stimulated pancreatic secretions. More uniform reductions were observed in the concentration and output of protein and enzymes. Individual variations were observed in the secretory volume and bicarbonate concentration and output. Amylase and lipase were depressed in a parallel fashion in seven patients and in the remaining three, amylase was more depressed than lipase. The post-glucagon reduction in pancreatic secretion was not proportional to the rise in plasma glucagon and blood glucose.

Effect of acetylcholine, gastrin, and glucagon alone and in combination with secretin and cholecystokinin on the secretion of the isolated perfused rat pancreas

Dose-response curves of acetylcholine (ACh), gastrin, and glucagon given alone or in combination with a submaximal dose of secretin (S;' 5.0 U/h) plus cholecystokinin (CCK; 1.0 U/h) were studied in the isolated perfused rat pancreas. ACh (25 x 10-9 mol/h) increased the basal secretory flow ( mean +/- SEM: 1.19 +/- 0.22 microliter/min) by 693% and protein output (2.7 +/- 0.2 microgram/min) by 1726%. The protein secretion evoked by S plus CCK was further increased by ACh to a maximum of 26% whereas the volume secretion remained unaltered. Gastrin (100 ng/h) stimulated the protein output by 352% and, when combined with S and CCK, up to further 23% and the secretory flow by 37%. Glucagon evoked a significant (P less than 0.005) increase of the protein output, but decreased the volume as well as the protein output (by 43% and 32%, respectively; P less than 0.05) when it was combined with the tested doses of S and CCK.