EFFECT OF RENIN-ANGIOTENSIN SYSTEM ON REGULATION OF PANCREATIC SECRETION IN CONSCIOUS RATS

Abstract

Background/Aim: Although previous studies have shown the presence of renin-angiotensin system (RAS) in the pancreas, the effect of RAS on regulation of pancreatic secretion has remained controversial. In the present study, we therefore investigated the effect of RAS on pancreatic secretion by using valsartan, a specific angiotensin II receptor blocker in conscious rats. Method: Male Wistar rats prepared with pancreatic, bilialy, duodenal, and intravenous cannulas were used in the study. Valsartan at a dose of 0, 1, 5, or 25 mg/kg was administrated into the duodenum, and volume of pancreatic fluid and protein output were determined for 4 hours. In addition, to examine the mechanism of action of RAS on pancreatic secretion, perivagal application of capsaicin (1 mg/rat) or intravenous infusion of atropine (100 μg/kg/hr) was conducted and then pancreatic secretion was examined after administration of valsartan at 25 mg/kg. Furthermore, to examine the influence of RAS on CCK or secretin-stimulated pancreatic secretion, valsartan at 25mg/kg was administrated and then pancreatic secretion was examined during intravenous infusion of CCK or secretin. Results: Pancreatic fluid secretion, but not protein output significantly decreased after administration of valsartan at 5 and 25 mg/kg. Perivagal application of capsaicin and intravenous infusion of atropine completely abolished the decrease in the pancreatic fluid secretion by valsartan. Valsartan at 25 mg/kg did not exert any effects on the CCK or secretin-stimulated pancreatic secretion. Conclusion: Present results suggest that pancreatic RAS participates in the stimulation of basal pancreatic fluid secretion via cholinergic pathway and has no influence on CCK or secretin-stimulated pancreatic secretion in conscious rats.