LIPID CHANGES IN HEPATIC MICROSOMES AND ITS RELATIONSHIP TO P-NITROPHENOL GLUCURONIDATION IN AN EXPERIMENTAL-MODEL OF PORTAL-HYPERTENSION

The liver is responsible for the most important metabolic pathway of n on polar compounds. The aim of the present work was to study the p-nit rophenol glucuronidation and its relationship with lipidic composition of microsomal membrane in a model of hepatic portal hypertension and hepatocellular damage induced by monocrotaline. A global increment in liver microsomal phospholipids as well as changes in the phospholipid pattern (phosphatidylethanolamine and sphingomyelin increased up to 15 6 +/- 13 and 195 +/- 14% respectively) were detected in monocrotaline intoxicated rats when it were compared to control rats. The microsomal cholesterol content showed a decrease in monocrotaline intoxicated ra ts. (4.1 +/- 0.7 against 6.6 +/- 1.5 mu g/mg of microsomal protein, in control rats). When p-nitrophenol activity was measured, Km from mono crotaline intoxicated rats was 0.137 mM, and Vmax was 2.9 nmol of p-ni trophenol/mg microsomal protein since in control group Km was 0,322 mM , and Vmax was 4,5 nmol of p-nitrophenol/mg microsomal protein. It is concluded that monocrotaline intoxicated rats showed a different behav ior in the kinetics of p-nitrophenol UDP-glucuronyltransferase,as well as a different microsomal lipidic profile, when compared to control g roup.