Clearance of bilirubin from rat brain after reversible osmotic opening of the blood-brain barrier.

Utilizing multicomponent spectrophotometry, we assayed the bilirubin content of rat cerebral hemispheres. With this assay, we determined the clearance of bilirubin from the rat brain following reversible, osmotic opening of the blood-brain barrier. Clearance was rapid, with a half-time of 1.7 h. This half-time was the same as that for clearance of bilirubin from the serum, suggesting that brain bilirubin was removed by transport or diffusion back into the general circulation. Osmotic opening does not damage brain tissue. Thus, in the undamaged rat brain, bilirubin is rapidly cleared, in contrast to its persistence in autopsy-proven human kernicterus. The potential for clearance of bilirubin from human neonatal brain should be considered, especially in the absence of underlying tissue damage.