Effects of nitroprusside on pancreatic juice secretion in the blood-perfused canine pancreas.

The effects of nitroprusside on the secretion of pancreatic juice were investigated in preparations of isolated and blood-perfused canine pancreas. Nitroprusside (10-30 micrograms/kg) injected intravenously elicited a dose-dependent increase in pancreatic secretion accompanied by a decrease in blood pressure. Intra-arterial administration of nitroprusside (3-300 micrograms) into the perfused pancreas also elicited an increased secretion in preparations of both constant pressure and constant flow perfusion system. The results suggest that nitroprusside-induced pancreatic secretion may not result from the peripheral vasodilatation caused by nitroprusside. The effect of 100 micrograms of intra-arterial nitroprusside corresponded roughly to that of 0.1 units of secretin or 0.3 units of pancreozymin. Nitroprusside-induced secretion was inhibited by the infusion of ethacrynic acid (1 mg/min), but was not modified by phentolamine, propranolol, atropine, haloperidol, tetrodotoxin and metiamide. Nitroprusside produced a dose-dependent increase in the bicarbonate and protein concentrations in the juice, but had little effect on chloride concentration. This action was different from that of secretin or pancreozymin. It is concluded that nitroprusside may produce an increase in pancreatic secretion by acting directly on pancreatic cells, and that this action may be mediated at least in part through the increase of intracellular cyclic GMP concentration.