Increased Bilirubin Production from Sources Other Than Circulating Erythrocytes in Mutant Southdown Sheep 1

Abstract

Summary

Bilirubin production from circulating erythrocytes and from other sources was studied in normal and mutant Southdown sheep with congenital hyperbilirubinemia. In mutant sheep, 66% on average of the total bilirubin produced originated from sources other than turnover of hemoglobin of circulating erythrocytes. This represented a 4-fold absolute increase above the bilirubin production rate from such other sources in normal sheep. Two separate “early-labeled” fractions were observed in both normal and mutant sheep following the injection of glycine-2-¹⁴C. Since mutant sheep exhibited no signs of ineffective erythropoiesis as evidenced by hypoplastic bone marrow and normal plasma and erythrocyte iron turnover, the hepatic overproduction of bilirubin should be considered and further investigated.