Increase of the Total Amount of Conjugated and Unconjugated Bilirubin in the Normothermic Perfused Isolated Dog Kidney System

Summary. The metabolism of bflirubin was studied in 36 isolated perfused dog kidney systems. When the plasma haemoglobin binding capacity was not saturated, and even. when it was so, the free plasma haemoglobin level being nevertheless lower than 50 rag/100 ml, there were no significant changes in the total amount of bilirubin in 7 male and 6 female isolated kidney perfusion systems during 7 h of perfusion. If the free plasma haemoglobin level was higher than 50 rag/100 ml during perfusion, there was a significant increase of 3.06 ~ 0.33 mg bilirubin in all 15 male kidney perfusion systems, and a significant rise of 2.92 =~ 1.07 mg bilirubin in 2 of the 11 female kidney perfusion systems. In the other 9 female systems, there was no significant change in the total amount of bilirubin after 6.5 h of perfusion. In the 15 male and the 2 female kidney perfusion systems there was an hourly production of 0.33 =[= 0.05 mg bilirubin as opposed to 0.03  0.01 mg in the other 3 groups. In the 15 males 74.0 ~= 5.2~ of the total amount of conjugated bilirubin was excreted in the urine, in the 2 females only 10  0.7~ It was concluded that all male and a few female kidneys converted significant amounts of free haemoglobin into bilirubin. The male kidney excreted this conjugated bilirubin in significant amounts, the female kidney did not do so.