Role of nitric oxide in the relationship of pancreatic blood flow and exocrine secretion in cats.

Abstract

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. In anesthetized cats, we determined the effects of the NO synthase inhibitor NG-monomethyl-L-arginine (10 mg/kg) and the NO donor sodium nitroprusside (10 micrograms.kg-1.min-1) on pancreatic secretion and blood flow (hydrogen gas clearance). NG-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, NG-monomethyl-L-arginine significantly reduced both secretin- and cholecystokinin-stimulated secretion. Sodium nitroprusside had no effect on basal blood flow but significantly increased secretion. 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.