Biliary bilirubin and biliverdin excretion in rabbits during fasting and feeding.

Biliary excretion rate of bilirubin and biliverdin from fasted and fed conscious rabbits has been investigated. The animals were cholecystectomized and fitted with a chronic surgical double recurrent choledoco-choledocal biliary fistula. The enterohepatic circulation of bile salts were maintained by bile administration. Mean bile flow, biliary concentrations and excretion rates of bilirubin and biliverdin remained constant during fasting conditions. After feeding bile flow and biliary output of biliverdin increased whereas that of bilirubin did not. The higher excretion rate of biliverdin after feeding could be explained by the low biliverdin reductase activity in this species and the stimulation of biliverdin formation by postprandial factors.