The Role of Nitric Oxide on Pancreatic Exocrine Function in Resting and Secretin Stimulated State

Lee, Hong Sik; Kim, Chang Duck; Hyun, Jin Hae

Abstract

BACKGROUND/AIMS: Recently NADPH-diaphorase has been detected in intrinsic neurons of the rat pancreas. So, nitric oxide(NO) should be considered as a putative neuronal mediator regulating pancreatic secretion(PS). We have investigated the role of NO on exocrine PS at resting and secretin-stimulated state.
METHODS
48 anesthetized male Sprague-Dawley rat(250 300g wt) were prepared with a tube in the proximal duodenum and pyloric ligation. Pancreatic duct was cannulated with PE-10 tubing, For a resting state or secretin stimulated state, each rat received an IV infusion of 0.5M NaC1(1.56ml/h) or secretin(10pM/kg/hr) for 1 h, respectively. L-NAME (Smg/kg), L-arginine (100mg/kg) and L-NAME(5mg/kg) plus L-arginine(100mg/kg) were IV administered(ad) in bolus at 30min after the onset of NaC1 or secretin infusion.
RESULTS
In resting state, the pancreatic secretory vo]ume(PS) and bicarbonate output(BO) were significantly suppressed by L-iVAME(20+2.7 vs 14.7 ' 2.6 pL/30min, 0.64+0.08 vs 0.480.08 pEq/30min respectively) and the PS and BO were significantly increased by L-arginine(19.6+2.3 vs 23.71.9 pL/30min, 0.61+0.07 vs 0.96+0.08 pEq/min respectively). The suppression of PS by L-NAME was reversed by IV ad of L-NAME plus L-arginine. In secretin-stimulated state, the PS and BO were not changed by L-NAME(25.4 3 vs 23.6>3.7 pL/30min, 0.83+0.09 vs 0.73+0.11 p Eq/30min respectively), but the PS and BO were significantly increased by L-arginine(23.2 2.3 vs 35.4+5.6 pL/min, 0.76>0.07 vs 1.16 -0.18 pEq/30min respectively).
CONCLUSIONS
These results suggest that nitric oxide is involved in resting pancreatic exocrine secretion, but not in secretin-stimulated pancreatic exocrine secretion.