NICOTINIC CHOLINERGIC INFLUENCES IN PANCREATIC-SECRETION INDUCED BY INTRADUODENAL ALKALINE AND ACID-SOLUTIONS IN THE RABBIT

1. The effect of hexamethonium on the exocrine pancreatic response to intraduodenal acidification and alkalinization, and the secretin and V IP release after these stimuli, was studied. 2. The hydroelectrolyte s ecretion after hydrochloric acid and sodium carbonate perfusion was re duced by hexamethonium treatment (322 +/- 44% of maximum response in f low rate to sodium carbonate perfusion in untreated animals vs 140 +/- 12% in pretreated animals, and 252 +/- 19% of maximum response in flo w rate to HCI in untreated animals vs 166 +/- 11% in pretreated animal s). 3. However, hexamethonium has no effect on secretin plasma levels after either intraduodenal acidification or alkalinization. 4. On the contrary, the ganglion blocker significantly (P < 0.0 1) reduced plasm a VIP levels in response to intraduodenal HCI (maximum response 320 +/ - 74% in untreated vs 184 +/- 44% in hexamethonium-treated animals). 5 . Plasma VIP levels showed a similar increase in both untreated (maxim um response: 151 +/- 12%) and ganglion blocked animals (170 +/- 26%) i n response to sodium carbonate. 6. These data suggest the existence of complex neural mechanisms in the exocrine pancreatic response to intr aduodenal stimuli, these mechanisms being different depending on the i ntraduodenal stimulus.