The risk of
bilirubin encephalopathy is believed to be increased in hemolytic relative to nonhemolytic
jaundice. Young SPRD rats were injected with either
acetylphenylhydrazine (APHZ, n = 22) 75 mg/kg or an equivalent volume of the
solvent (control, n = 22) intraperitoneally for 3 successive days. One the 4th day,
hyperbilirubinemia was induced by a 5-min
intravenous infusion of 50 mg/kg
bilirubin. After sacrifice (
at 10 or 60 min) the brain vessels were flushed in situ with
ice-cold saline. Serum
bilirubin was 600 +/- 108 mumol/l (mean +/- SD)
at 10 min, and 295 +/- 98 mumol/l at 60 min. Hematocrit was significantly reduced in the APHZ rats versus controls (26 +/- 3 vs. 41 +/- 3, p < 0.0001). The concentration of
bilirubin in brain was determined by
acid chloroform extraction and diazotization. The brain
bilirubin values were 5.5 +/- 1.5 versus 5.4 +/- 2.1 mmol/g
at 10 min (APHZ vs. control), and 1.3 +/- 0.6 versus 0.8 +/- 0.7 nmol/g at 60 min. The half-life of
bilirubin in brain was calculated with an exponential fitting program. The half-life of
bilirubin in brain for the two groups was 24.3 +/- 21.9 versus 18.5 +/- 28.3 min. There were no significant differences between the groups in either of these measures. We conclude that in young rats,
hemolytic anemia does not increase the acute entry of
bilirubin into brain, nor does it affect the clearance of
bilirubin from brain.