Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.17.3.2 (xanthine oxidase)
 8,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Perfused rat liver was used to study the relationship between the hepatotoxic effects of hyperthermia and the effects of heat on lysosomes. Livers from fed rats were perfused for 180 min at 37-43 degrees C. Release of lysosomal enzymes into the perfusate during perfusion and lysosomal fragility at the end of perfusion were determined. Lysosomes were then incubated in vitro at 37-45 degrees C with xanthine and xanthine oxidase to generate superoxide in order to study lipid peroxidation as a potential causative factor in heat-induced lysosomal lability. Perfusate lysosomal enzymes p-nitrophenyl phosphatase and beta-glucuronidase increased significantly (P less than 0.05) at 42 and 43 degrees C over enzyme levels at 37 degrees C. Significant differences were not observed until after 120 min. Lysosomal fragility was found to be significantly increased (P less than 0.05) after perfusion at 42 and 43 degrees C when measuring p-nitrophenyl phosphatase, but not when measuring beta-glucuronidase activity. Xanthine oxidase acting on xanthine caused labilization of the lysosomes at all temperatures studied when compared to a control at each temperature. There was a temperature effect with an increase in release of p-nitrophenyl phosphatase and beta-glucuronidase from control lysosomes which became significant (P less than 0.05) at 43 degrees C on comparison to 37 degrees C. There were no significant increases in lysosomal lability with temperature in the presence of xanthine and xanthine oxidase. Lastly, salicylic acid peroxidation was used as a measure of superoxide formation from the action of xanthine oxidase with increasing temperature.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Hyperthermic liver perfusion and release of lysosomal enzymes. 282 85

Effects of arachidonic acid on cellular metabolism, cation content, lipid peroxidation, sodium pump activities and release of labeled arachidonic acid were studied in C-6 glioma cells and N18TG2 neuroblastoma cells. Arachidonic acid caused a significant increase in intracellular sodium levels concomitant with a decrease in intracellular potassium in both cell lines. Both (Na+ + K+)-ATPase and p-nitrophenyl phosphatase of glioma cells were inhibited by arachidonic acid whereas only the p-nitrophenyl phosphatase of neuroblastoma cell was inactivated. Low concentrations of arachidonic acid stimulated lactic acid release whereas high concentrations had an opposite effect. In addition, the lipid peroxide content of glioma cells was increased abruptly by 50 microM arachidonic acid whereas only a slight increase of malondialdehyde was observed in neuroblastoma cells. When the cultured cells of both cell lines were incubated with exogenous labeled arachidonic acid, 78-95% of the label was incorporated into membrane phospholipids. Only a very small fraction of prostaglandin E2 and prostaglandin F2 alpha was synthesized. Exogenous arachidonic acid and free radicals generated with xanthine-xanthine oxidase caused a significant release of endogenous labeled arachidonic acid from cellular membrane phospholipids. These data further support our hypothesis that the arachidonic acid and its oxygen radical metabolites induce pathological alterations in membrane permeability and cellular volume.
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PMID:Alterations of membrane integrity and cellular constituents by arachidonic acid in neuroblastoma and glioma cells. 628 88