LIVER MICROSOMAL PHOSPHOLIPID FATTY-ACIDS BEHAVIOR AND ITS RELATIONSHIP TO BILIRUBIN UDP-GLUCURONOSYLTRANSFERASE ACTIVITY IN BILE-DUCT LIGATED RATS

Phospholipid fatty acid composition and bilirubin UDP-glucuronyltransf erase activity from liver microsomal membrane were studied in normal a nd in bile duct ligated rats. Incubation of normal microsomes with 15 mu M bilirubin (considered as physiological concentration) yielded 60% bilirubin diglucuronide; in 2 days post-cholestatic rats, they showed 20% bilirubin diglucuronide which was undetectable in 8 days post-cho lestatic group. When compared to controls, after 2 days of cholestasis , microsomal phospholipids showed a clear decrease in linoleic and ara chidonic acids and an increment in palmitic and stearic acids. 8 days post-cholestatic rats presented a marked increase in palmitic, oleic a nd docosaexaenoic acids, while linoleic and arachidonic acids decrease d. Cholestasis produced disturbances in microsomal phospholipids fatty acid composition; but these changes are unable to explain entirely th e severe damage observed in bilirubin diglucuronide formation.