XANTHINE OXIDOREDUCTASE GENE-EXPRESSION AND ENZYME-ACTIVITY IN DEVELOPING HUMAN TISSUES

Xanthine oxidoreductase (XOR) has been implicated in tissue injury fol lowing ischemia-reperfusion because of its ability to generate reactiv e oxygen species under these conditions. In order to elucidate its rol e in various organs, we quantified the levels of XOR mRNA expression a nd activity in developing human tissues. XOR gene expression was highe st in the intestine and in the liver, which also showed the highest en zyme activities. By a sensitive RNA-PCR assay, low levels of the trans cript were detected in the kidney, lung, cardiac muscle, and brain of all subjects studied. XOR activities followed the mRNA distribution, b eing low or undetectable in tissues other than the liver and the intes tine.