Biphasic action of intravenous ethanol on dog exocrine pancreatic secretion

The effect of a 20-min intravenous infusion of 1 g/kg of ethanol on a 15% (w/w) solution in isotonic saline on pancreatic secretion was determined in six conscious Beagle dogs provided with Thomas cannulae. Ethanol was given on a background of a prolonged infusion of 0.5 CU/kg/hr of secretin alone or secretin plus either different doses of cerulein (12.5-200 ng/kg/hr), 3 micrograms/kg/hr of pentagastrin, or 200 micrograms/kg/hr bethanechol. Intravenous ethanol had a biphasic action on pancreatic secretion: inhibition during the first 40 min followed by stimulation. When compared to control experiments with intravenous infusion of saline, the inhibition was statistically significant only for volume and bicarbonate output against a background of pentagastrin and for protein output against a background of bethanechol. We propose that alcohol inhibits acetylcholine-mediated protein secretion. The delayed stimulatory effect of ethanol was statistically significant for both ecobolic (protein output) and hydralatic (water and bicarbonate) secretion during infusion of secretin plus 12.5-25 ng/kg/hr cerulein, but not with doses of 50 ng/kg/hr. Although the plateau of secretion before alcohol was roughly similar in the experiments using cerulein and bethanechol, ethanol inhibited protein output and had no effect on bicarbonate output during stimulation with bethanechol. Therefore, the effects of alcohol on pancreatic secretion are influenced by both the type of stimulation and its intensity (dosage).