The acute and chronic effects of ethanol administration on bile secretion in the rat

Either a 25 per cent solution of 95 per cent ethanol or isocaloric glucose in drinking water was pair-fed with lab chow to 300 Gram male Sprague-Dawley rats for 2 weeks. These diets allowed 28.4 per cent of calories as either ethanol or glucose and sustained growth. At the end of 2 weeks, bile secretory function was assessed. Liver and body weights were similar in the 2 pair-fed groups. When blood ethanol levels were negligible at the time of study, bile flow and bile salt secretion were significantly increased in the animals fed ethanol. Bile-to-plasma ratios of ¹⁴C-erythritol approximated 1.0 in both pair-fed groups, and estimates of canalicular bile flow suggested that ethanol was stimulating a bile canalicular secretory mechanism. Comparison of regression lines of bile salt secretion vs. flow indicated that ethanol significantly increased the nonbile salt-dependent fraction of bile (p < 0.01) in the majority of animals. The rate of bile salt excretion was also enhanced in the ethanol-fed animals. Augmentation of the nonbile salt-dependent fraction of bile-flow was not associated with an increase in the biliary excretion of hexuronic acids. In contrast, bile flow was depressed when blood levels of ethanol were elevated at the time of study or when ethanol was added acutely to the perfusate of normal isolated rat liver preparations. These findings indicate that ethanol may either inhibit or stimulate bile secretion depending on the blood alcohol level and duration of intake and that chronic ethanol feeding is associated with stimulation of the nonbile salt-dependent fraction of canalicular bile flow in the rat.