Postnatal development of hepatic bile formation in the rabbit.

To investigate postnatal maturation of hepatic bile formation, bile output was measured in four groups of rabbits: suckling infants at ages 10-14, 18-22, and 26-30 days, and adults. Bile output was collected directly from the common duct during three 1-hr periods: a basal period followed by intravenous infusion of 1 and then 2 mumol/min/kg of glycodeoxycholic acid. [14C]Erythritol and [3H]inulin clearances measured canalicular bile flow and biliary permeability. Under basal conditions and with the exogenous bile acid, bile flow and bile salt secretion were lowest in 10- to 14-day-old infants and showed a gradual increase with increasing age. Bile salt-dependent flow, the linear increase in flow relative to bile salt secretion, was higher in the 10- to 14- and 17- to 22-day-old compared to the adult and 25- to 30-day-old groups. The ratio of chloride to bile salt secreted was also higher in the two younger groups. Bile salt-independent flow at theoretical zero bile salt secretion was absent in the younger groups, but evident in the adult and 25- to 30-day-old rabbits. Canalicular flow estimated by erythritol clearance was linearly related to bile salt secretion. Inulin clearance relative to erythritol clearance was higher in the 10- to 14-day-old infants than the adults. Thus, bile flow and bile salt secretion are reduced in the young infant but rise to near adult levels at the time of weaning, 25-30 days in the rabbit. The increase in flow results from increased bile salt secretion and the appearance of bile salt-independent flow.(ABSTRACT TRUNCATED AT 250 WORDS)