Kooij A, Frederiks W M, Gossrau R, Van Noorden C J
Laboratory of Cell Biology and Histology, University of Amsterdam, The Netherlands.
J Histochem Cytochem. 1991 Jan;39(1):87-93. doi: 10.1177/39.1.1983876.
We have detected xanthine oxidoreductase activity in unfixed cryostat sections of rat and chicken liver, rat duodenum, and bovine mammary gland using the tissue protectant polyvinyl alcohol, the electron carrier 1-methoxyphenazine methosulfate, the final electron acceptor Tetranitro BT, and hypoxanthine as a substrate. Enzyme activity was localized in rat duodenum at lateral membranes and brush borders of enterocytes and in goblet cells and mucus. Hepatocytes in pericentral areas and especially sinusoidal cells showed high activity in rat liver. Xanthine oxidoreductase was also detected in epithelial cells and milk lipid globules of lactating bovine mammary gland, which is known to contain large quantities of the oxidase form of the enzyme. Chicken liver, which contains an inconvertible dehydrogenase form, also showed high activity in sinusoidal cells. Therefore, we conclude that the tetrazolium reaction demonstrates both the dehydrogenase and the oxidase form of xanthine oxidoreductase. Control activity, in the absence of hypoxanthine or in the presence of the competitive inhibitor allopurinol, was low in all tissues studied. Addition of O2 or NAD to the incubation medium did not change the specific reaction in bovine mammary gland or chicken liver, implying that the dehydrogenase and the oxidase form are not dependent on their natural electron acceptors in this tetrazolium salt reaction. We conclude that the present light microscopic method gives specific and precise localization of xanthine oxidoreductase activity in situ.
我们使用组织保护剂聚乙烯醇、电子载体1-甲氧基吩嗪甲磺酸盐、最终电子受体四硝基BT以及次黄嘌呤作为底物，在大鼠和鸡肝脏、大鼠十二指肠以及牛乳腺的未固定低温恒温器切片中检测到了黄嘌呤氧化还原酶活性。酶活性定位于大鼠十二指肠肠上皮细胞的侧膜和刷状缘、杯状细胞以及黏液中。大鼠肝脏中央周围区域的肝细胞，尤其是窦状隙细胞显示出高活性。黄嘌呤氧化还原酶也在泌乳期牛乳腺的上皮细胞和乳脂肪球中被检测到，已知该器官含有大量该酶的氧化酶形式。鸡肝脏含有不可转化的脱氢酶形式，其窦状隙细胞也显示出高活性。因此，我们得出结论，四唑盐反应显示了黄嘌呤氧化还原酶的脱氢酶和氧化酶形式。在所有研究的组织中，在没有次黄嘌呤或存在竞争性抑制剂别嘌呤醇的情况下，对照活性都很低。向孵育培养基中添加O₂或NAD不会改变牛乳腺或鸡肝脏中的特异性反应，这意味着在这种四唑盐反应中，脱氢酶和氧化酶形式不依赖于它们天然的电子受体。我们得出结论，目前的光学显微镜方法能够在原位对黄嘌呤氧化还原酶活性进行特异性和精确的定位。
