Effects of nitroglycerin on pancreatic exocrine secretion and cyclic nucleotide concentrations of the dog pancreas.

The effects of nitroglycerin on the secretion of pancreatic juice and on the intracellular levels of cyclic nucleotides were investigated in preparations of the isolated, blood-perfused dog pancreas. Nitroglycerin (10-30 micrograms) injected intra-arterially caused a dose-dependent increase in the secretion of pancreatic juice within 30 sec. The concentration of protein in the pancreatic juice induced by nitroglycerin was increased. However, bicarbonate concentration was increased slightly. Nitroglycerin-induced secretion was not modified by pretreatment with phentolamine, propranolol, atropine, metiamide and sulpiride. Nitroglycerin increased cyclic GMP concentration in the pancreatic tissue within 2 min associated with the secretion of pancreatic juice. On the other hand, cyclic AMP concentration was not influenced significantly throughout 30 min after the administration of nitroglycerin. From these results, it is concluded that nitroglycerin may produce an increase in pancreatic secretion mediated through an increase of intracellular cyclic GMP concentration.