Secretory and vascular responses to 1,1-dimethyl-4-phenylpiperazinium (DMPP) of the blood-perfused canine pancreas.

Effects of DMPP on the secretory and vascular responses were investigated in preparations of the isolated, blood-perfused canine pancreas. DMPP (10-300 micrograms) injected intra-arterially caused a dose-dependent increase in the secretion of pancreatic juice with a transient vasodilation followed by a long-lasting vasoconstriction. The secretory activity of 300 micrograms of DMPP was approximately equal to that of either 100 micrograms of acetylcholine or 0.07 units of secretin. DMPP-induced pancreatic secretion and vasodilation was completely inhibited by pretreatment with tetrodotoxin, hexamethonium, atropine and attenuated by haloperidol. DMPP-induced vasoconstriction was suppressed by tetrodotoxin, hexamethonium and phentolamine. DMPP increased protein concentration in the pancreatic juice. This action was similar to that of acetylcholine and different from that of secretin. From these results, it is suggested that the secretory and vascular responses to dMPP are due to the stimulation of both parasympathetic and sympathetic ganglia.