Reduction of biliverdin to bilirubin in tissues

Abstract

The livers of all species (man, horse, cat, rat, mouse, Echidna, fowl, pigeon, frog) investigated are able rapidly to reduce biliverdin to bilirubin under aerobic conditions, the reaction being effected by a number of dehydrogenase systems and by ascorbic acid; in the enzymic reduction aldehydes, glucose, alcohol, citrate and formate can act as H donators, the aldehydes being activated by proteins and by an aldehydrase (distinct from xanthine oxidase). Spleen, kidney and brain of the guinea pig are also able to reduce biliverdin aerobically and all other tissues of this species except skin can do so anaerobically. The results are in accord with the hypothesis that biliverdin is the primary bile pigment, bilirubin being formed from it by reduction in the tissues.