Exogenous cysteamine increases basal pancreatic exocrine secretion in the rat

To determine whether exocrine pancreatic secretion is regulated by endogeno us somatostatin, somatostatin deficiency was induced by cysteamine. Rats we re subcutaneously administered a single dose of cysteamine (30 mg/100 g bod y weight) 12 hr before experiment. Anesthetized rats were prepared with can nulation into bile duct, pancreatic duct, duodenum, and jugular vein and pa ncreatic juice was collected. For in vitro study, isolated pancreata of rat s, pretreated with cysteamine, were perfused with an intraarterial infusion of Krebs-Henseleit solution (37 degrees C) at 1.2 mL/min, and pancreatic j uice was collected in 15-min samples. In vivo experiment of the rat, the me an basal pancreatic secretions, including volume, bicarbonate, and protein output were significantly increased from 18.4+/-0.5 mu L/30 min, 0.58+/-0.0 5 mu Eq/30 min, and 214.0+/-26.1 mu g/30 min to 51.6+/-3.7 mu L/30 min, 1.5 2+/-0.11 mu Eq/30 min, and 569.8+/-128.9 mu g/30 min, respectively (p<0.05) . In the isolated perfused pancreas, cysteamine also resulted in a signific ant increase in basal pancreatic secretion (p<0.05), Simultaneous intraarte rial infusion of octreotide (10 pmol/hr) to isolated pancreata partially re versed the effect of cysteamine on basal pancreatic secretion. These findin gs suggest that endogenous somatostatin play an important role on the regul ation of basal pancreatic exocrine secretion.