Insulin-stimulated bile formation in cats.

The effects of insulin on bile flow and composition were examined in fasting, chloralose-anesthetized cats. Insulin in doses from 0.01 to 2.00 U/kg increased bile flow and biliary erythritol clearance without any detectable change in the difference between them; thus insulin presumably had no effect on ductular fluid transport. Continuous infusion of insulin (0.8 U/kg+0.05 U/kg/min or 0.05 U/kg+0.002 U/kg/min) increased biliary erythritol clearance by 22%. The increase was caused by a rise in the bile acid-independent fraction of bile production and accompanied by a parallel increase in the rates of biliary excretion of Na+ and Cl-. When ouabain, 80 micrograms/kg, was injected intraportally during insulin infusion the erythritol clearance, bile flow and the rates of biliary excretion of Na+ and Cl- were lowered towards but not to their preinsulin levels. The effects of insulin on these parameters were unchanged after atropin or gastrectomy and 2-Deoxy-D-Glucose was without effect on bile production. The results indicate that administration of insulin affects bile formation by stimulating the active transport of sodium across the canalicular membrane.