Effects of bombesin on fasting bile formation.

Adult dogs were previously prepared by cholecystectomy, ligation of the lesser pancreatic duct, and insertion of cannulae into the duodenum and stomach. After a 2-week period of postoperative recovery and an overnight fast, bile ducts were cannulated, gastric cannulae placed to open drainage and sodium taurocholate 500 mg hr-1 was administered to replace bile acids lost from the interrupted enterohepatic circuit. Bombesin was infused IV for 1 hour over the dose range, 0.625-10 ng kg-1 min-1. In control experiments 0.15 N NaCl was infused. Bombesin caused a significant increase in fasting bile flow, 3.0 +/- 0.2 ml/15 min to 4.2 +/- 0.3 ml/15 min (40%). Bile acid and phospholipid outputs were unchanged during bombesin. Bile cholesterol output decreased significantly during bombesin, 1029 +/- 142 micrograms/15 min to 856 +/- 109 micrograms/15 min (17%). The increase in bile flow was linearly related to the logarithm of the bombesin dose. In dogs with pyloric occlusion, to prevent acid from reaching the duodenum, bombesin increased bile flow and bicarbonate output but had no effect on 14C erythritol biliary clearance. Bombesin stimulated ductular bile acid independent bile formation in a dose-dependent manner. Bombesin also inhibited bile cholesterol output.