Further studies on the effect of cholecystokinin and secretin on the content of cyclic AMP, cyclic GMP, protein and calcium in pure pancreatic juice of dogs.

The present work deals with the time course of pancreatic secretion of cyclic AMP, cyclic GMP, calcium and protein in response to cholecystokinin (CCK) and secretin (S). Three dogs with gastric and duodenal Thomas cannulae were given 1 Clinical Unit/kg/h of secretin for 150 min. CCK was added to the infusion after the first 75 min. Only one dose of CCK (0.75, 1.5, 3, 6, 16 24 Ivy dog U/kg/h) was given in any one experiment. Pancreatic juice was collected at one minute intervals for the first 15 min. at the beginning of the CCK infusion and at 15 min. intervals thereafter. CCK induced a biphasic pattern of pancreatic secretion: within 3 to 10 min. flow rate, protein, calcium, cyclic AMP and cyclic GMP output peaked in a dose dependent parallel manner. Then, the maximal flow remained constant while protein output reached a steady state; its value was fairly similar to that of the early peak for 0.75 to 6 U and for 16 and 24 U, the steady state value was lower than the first peak value. The pattern of calcium output was similar to that of protein output. The output of cyclic AMP and cyclic GMP increased until the end of the CCK infusion. When CCK (3 U/kg) was given as an intravenous bolus injection without any background of secretin, cyclic AMP, cyclic GMP and protein outputs peaked within 3 min. and then decreased. The results show that not only calcium and protein but also cyclic AMP and cyclic GMP secretion in the pancreatic juice depends on CCK. Key words: Dog, secretin, cholecystokinin, pancreatic juice: cyclic AMP, cyclic GMP, calcium, protein.