Lochner F, Sherban D G, Sangiah S, Mauromoustakos A
Department of Medicine and Surgery, College of Veterinary Medicine, Oklahoma State University, Stillwater 74078.
Res Vet Sci. 1990 Jul;49(1):104-9.
Using a modified bovine milk enzyme kinetic assay, xanthine oxidase activity of serum collected from 34 adult, healthy horses of both sexes was determined. Enzyme activity varied from 0 to 126 mU litre-1 with a mean of 44.95 +/- 21.05 mU litre-1. The optimal pH and temperature for maximal activity were 7.8 and 28 degrees C, respectively. Freezing the serum for four days at -70 degrees C did not destroy the enzyme activity. Various doses (25, 50 and 75 micrograms kg-1, intraperitoneally) of endotoxin (lipopolysaccharide D1 Escherichia coli O26:B6) previously known to have caused moderate to severe systemic clinical signs of endotoxaemia in horses produced a significant dose related increase in serum xanthine oxidase activity. Pretreatment (12 hours) with allopurinol (5 and 50 mg kg-1, intravenously [corrected]) significantly reduced the rise in xanthine oxidase activity in endotoxin (50 micrograms kg-1, intraperitoneally) treated horses. The results of this study suggest that xanthine oxidase catalysed production of superoxide radicals may play a role in the pathogenesis of endotoxaemia and that allopurinol, an alternate substrate, should be further evaluated for its therapeutic potential in endotoxin related systemic diseases in horses.
采用改良的牛乳酶动力学分析法，测定了从34匹成年健康雌雄马采集的血清中的黄嘌呤氧化酶活性。酶活性范围为0至126 mU/L，平均为44.95±21.05 mU/L。最大活性的最佳pH值和温度分别为7.8和28℃。血清在-70℃冷冻4天不会破坏酶活性。先前已知能在马身上引起中度至重度内毒素血症全身临床症状的各种剂量（25、50和75微克/千克，腹腔注射）内毒素（脂多糖D1大肠杆菌O26:B6）导致血清黄嘌呤氧化酶活性出现显著的剂量相关增加。用别嘌醇（5和50毫克/千克，静脉注射[校正]）预处理（12小时）可显著降低内毒素（50微克/千克，腹腔注射）处理的马的黄嘌呤氧化酶活性升高。本研究结果表明，黄嘌呤氧化酶催化产生超氧自由基可能在内毒素血症的发病机制中起作用，并且别嘌醇作为一种替代底物，应进一步评估其在马内毒素相关全身性疾病中的治疗潜力。
