DEGRADATION OF HEME-IX IN RATS PRETREATED WITH COBALTOUS CHLORIDE - ASTUDY IN ISOLATED-PERFUSED LIVER

The effect of the administration of cobaltous chloride on the degradat ion of heme IX was investigated using perfusions of isolated rat liver s. The presence of biliverdin IX beta (2%) in the bile fluid of cobalt ous chloride treated rats support the hypothesis of the presence of a chemical oxidation of heme IX induced by the cobalt salt. In control r ats the absence of biliverdin IX beta in the bile fluid was observed. When biliverdin IX beta was added to the perfusate it was excreted in the bile fluid as bilirubin IX beta without conjugation. An increase f rom approximately twofold to three-fold of the total bilirubins in the bile fluids of cobaltous chloride pretreated rats in relation with co ntrol rats was observed due to heme oxygenase enhanced activity. Bilir ubin IX alpha diconjugates increased ca. 15% in the bile fluids of cob altous chloride pretreated rats, after the addition of hemin IX. The i ncrease could reflect the presence of a new molecular form of UDP-gluc uronosyltransferase, which favours the formation of bilirubin IX alpha diglucuronide and therefore its preferential excretion into the bile. In the bile fluid of the rats pretreated with cobaltous chloride, oth er diconjugates of bilirubin IX alpha were also detected 120 min after the addition of hemin IX to the perfusate, consisting of glucose and glucuronate (5%) end xylose and glucuronate (5%).