Erythrocytic enzyme activities and drug induced hemolysis in rabbits

Xylitol mediated amelioration of acetylphenylhydrazine-induced hemolysis in rabbits

Xylitol was investigated for its ability to ameliorate hemolytic anemia induced by acetylphenylhydrazine in rabbits. Animal experiments were performed using two different concentrations of xylitol, a 5% and a 10% solution with a total dose of 2 g/kg body weight and infusion rates of 10 mg and 20 mg xylitol per kg body weight per minute respectively. Two doses of acetylphenylhydrazine (APH), 5 and 10 mg per kg, were injected intraperitoneally as hemolytic inducers in different groups of rabbits. All the rabbits infused with xylitol showed significantly less acute APH-induced hemolysis. The isotonic 5% xylitol solution was found to maintain and restore the hematological parameters (packed cell volume, hemoglobin concentration, reduced glutathione (GSH) content, and reticulocyte counts) better than the 10% xylitol solution. Increased 51CR-red cell survival confirmed the beneficial effect of xylitol. The survival of erythrocytes as represented by chromium-labeling in rabbits infused with 5% xylitol after treatment with 10 mg/kg APH increased from about 33% (the survival of red cells in rabbits injected with APH alone) to 67% of normal rabbits' red cell survival. Erythrocytes in APH-treated animals took up xylitol more readily than erythrocytes from control animals. Our results in rabbits suggest that (1) non-toxic dosage of xylitol is effective in ameliorating the hemolytic episode induced by APH, (2) there is a dose relationship between the hemolytic effect induced by APH and the preventive effect offered by xylitol, (3) drug-challenged cells effectively acquired two to three fold more xylitol to compensate for the cellular needs than that of the normal cells, and (4) sufficient xylitol (55 mg/dl) to act as substrate for xylitol dehydrogenase was recovered intracellularly in drug-challenged rabbit erythrocyte in vivo, in spite of a low plasma (less than 30 mg/dl) concentration of the substrate. This antihemolytic affect of xylitol is likely accomplished through NADPH generation, which maintains the level of GSH and protects the hemoglobin and other structural and functional proteins against peroxidative damage.