ROLE OF NITRIC-OXIDE IN THE RELATIONSHIP OF PANCREATIC BLOOD-FLOW AND EXOCRINE SECRETION IN CATS

Background/Aims: Recent studies have suggested that, in the gastrointestinal tract, nitric oxide is an important mediator of alterations in blood flow and, in some organs, a second messenger involved in secretion. This study examined the role of NO in changes in pancreatic blood flow associated with basal and stimulated pancreatic exocrine secretion. Methods: In anesthetized cats, we determined the effects of the NO synthase inhibitor N-G-monomethyl-L-arginine (10 mg/kg) and the NO donor sodium nitroprusside (10 mu g . kg(-1). min(-1)) on pancreatic secretion and blood flow (hydrogen gas clearance). Results: N-G-monomethyl-L-arginine had no effect on the increase in blood flow associated with secretin stimulation (271 +/- 52 vs. 290 +/- 50 mL . min(-1). 100 g(-1)) but reduced that associated with cholecystokinin stimulation (189 +/- 17 vs. 53 +/- 15 mL(.) min(-1). 100 g(-1); P < 0.001). In contrast, N-G-monomethyl-L-arginine significantly reduced both secretin- and cholecystokinin-stimulated secretion. Sodium nitroprusside had no effect on basal blood flow but significantly increased secretion. Conclusions: NO has a selective role in mediating changes in pancreatic perfusion and secretion. It seems to be important in stimulus-secretion coupling with both secretin and cholecystokinin but is only responsible for the accompanying increase in pancreatic blood flow with cholecystokinin.