Pancreatic secretory responses in L-arginine-induced pancreatitis: Comparison of diabetic and nondiabetic rats

The aim of this work was to study cholecystokinin-octapeptide (CCK-8)-stimu lated pancreatic secretion after the induction of pancreatitis with L-argin ine (ARG) in rats with or without streptozotocin (STZ) diabetes. One, 3, 7, and 14 days after pancreatitis induction, rats were surgically prepared wi th pancreatic duct and femoral vein cannulae under urethane anesthesia. Gra ded doses of CCK-8 ranging from 9 to 2,400 ng/kg/30 min were administered i ntravenously. In the control group, the step-wise increasing doses of CCK-8 resulted in a characteristic dose-response curve for the pancreatic volume , protein and amylase secretion (maximal volume, protein and amylase output at 600 ng/kg/30 min of CCK-8: 157 +/- 20.2 mu l/30 min, 28.3 +/- 1.18 mg/3 0 min, and 3,750 +/- 92 IU/30 min, respectively). In rats with pancreatitis , the pancreatic volume (both basal and maximal) and amylase secretion were significantly elevated on day 1 versus the control group; then on days 3, 7, and 14, the pancreatic secretory volume and amylase were progressively a nd significantly decreased versus the control group. However, the protein o utput was continuously decreased versus the control group on days 1, 3, 7, and 14. In diabetic rats, the maximal volume and protein and amylase output were all significantly decreased versus the control group throughout the e xperiment. In the diabetes + pancreatitis group, the maximal volume and pro tein and amylase output were all significantly increased versus the diabete s group on days 1, 3, 7, and 14. These results indicate that in the early p hase of ARG-induced pancreatitis, the pancreatic secretion is characterized by increases in secretory volume and amylase, with a simultaneous decrease in protein output. Simultaneous diabetes seems to moderate the CCK-8-stimu lated secretory changes in both the early and late phases after ARG-induced pancreatitis.