TRANSFER OF BILIRUBIN FROM BLOOD TO BILE IN NEONATAL GUINEA PIG

Extract: The development of hepatic uptake, conjugation, and excretion of bilirubin was investigated in newborn and in adult guinea pigs. Excretion of conjugated bilirubin from liver is rate-limiting in the overall transfer of bilirubin from plasma to bile in newborn as well as in mature guinea pigs. Hepatic excretion of bilirubin gradually matures during the first three weeks of life. Glucuronyl transferase activity was also reduced in liver from newborn guinea pigs less than 72 hours old, but the limitation was apparently insufficient to be rate-limiting in vivo. Cumulative hepatic uptake of bilirubin by the liver was also reduced during the newborn period and achieved adult levels at approximately 15 days of age. The rate of endogenous bilirubin excretion was the same in newborns of all ages and in adults, suggesting that erythrocyte life span and bilirubin synthesis are similar in newborn and in adult guinea pigs. Speculation:Hepatic uptake, conjugation, and excretion of bilirubin are reduced in neonatal guinea pigs that do not manifest physiologic hyperbilirubinemia. Similar studies should be performed in species that have neonatal jaundice. The contribution of impaired hepatic uptake of bilirubin to physiologic jaundice of human infants warrants further study. © International Pediatrics Research Foundation, Inc. 1969. All Rights Reserved.