Permeability of the blood brain barrier for 125I-albumin-bound bilirubin in newborn piglets.

Abstract

Permeability of the blood brain barrier (BBB) for bilirubin and 125I-albumin was studied in 2-d- and 2-wk-old piglets. 125I-albumin was given by bolus at the beginning of each study. Hyperbilirubinemia was produced by an initial bolus infusion of bilirubin and sustained at a plasma bilirubin:albumin molar ratio of approximately 1.0 by continuous infusion of bilirubin for 3 h. During the study period, arterial pH and blood gas tensions, serum osmolarity, and mean arterial blood pressure were within the physiologic range for age in both groups. Serum albumin and serum total and unbound bilirubin concentrations were higher in the 2-wk-old piglets. Brain bilirubin concentrations and permeability (P.S product) of the BBB for bilirubin were higher in the 2-d-old than in the 2-wk-old piglets, but the values of P.S for albumin were not different between the two groups. In 2-d-old piglets, regional brain bilirubin concentrations and permeability of the BBB were higher in subcortical regions (cerebellum and brainstem) than in the cerebral cortex. Regional brain albumin concentrations and BBB permeability to albumin in 2-d-old piglets were higher only in the cerebellum. In all regions, the bilirubin:albumin molar ratio was higher in the brain tissues than in the blood. In 2-wk-old piglets, the brain concentrations and P.S products for bilirubin were lower and the regional differences were less marked than for 2-d-old animals.(ABSTRACT TRUNCATED AT 250 WORDS)