EVIDENCE FOR ACCELERATED GENERATION OF HYDROXYL RADICALS IN EXPERIMENTAL OBSTRUCTIVE-JAUNDICE OF RATS

We present evidence herein of the accelerated generation of hydroxyl r adical ((OH)-O-.) in the plasma and the liver tissue of common bile du ct ligated (CBDL) rats, a model for experimental obstructive jaundice. (OH)-O-. production in the plasma was monitored in vivo by the identi fication of dihydroxybenzoates in plasma [2,3-dihydroxybenzoate (2,3-D HB) and 2,5-dihydroxybenzoate (2,5-DHB)] using high performance liquid chromatography (HPLC). The average concentrations of 2,3-DHB and 2,5- DHB produced in the plasma of the controls were 33 +/- 3 mu M and 232 +/- 34 mu M (n = 15), respectively, whereas their respective concentra tions increased to 149 +/- 28 mu M and 604 +/- 88 mu M in the CBDL rat s (n = 19). Furthermore, we also observed a time-dependent decreasing trend of 2,3-DHB and 2,5-DHB production after surgical removal of the ligation of the experimental animals. In addition, the generation of ( OH)-O-. in the liver tissue was studied by using dimethyl sulfoxide (D MSO) as a molecular probe and measuring the amount of methanesulfinic acid (MSA), the product of the trapping reaction. The net production o f MSA in the liver tissue of the control rats was 1.22 +/- 0.05 O.D. u nit/g protein (n = 5), whereas its respective concentration of MSA in the liver tissue of CBDL rats increased to 2.05 +/- 0.15 O.D. unit/g p rotein (rt = 5). In addition, we showed that CBDL rats receiving a pre treatment of mannitol, an (OH)-O-. scavenger, resulted in the decrease d production of MSA, Electron micrographic study indicated that the mo st prominent change observed in CBDL rats was the alteration of mitoch ondria, which were swollen with distorted cristae. Meanwhile, the bile canaliculi were moderately more dilated than that of the controls, an d an increased neutrophil peripheral blood count was found in CBDL rat s when compared to the controls. Taken together, our data suggest that accelerated generation of (OH)-O-. in the CBDL rats is obvious and ma y play a key role in the pathogenesis of liver damage associated with obstructive jaundice. (C) 1998 Elsevier Science Inc.