Punch J, Rees R, Cashmer B, Wilkins E, Smith D J, Till G O
Section of Plastic and Reconstructive Surgery, University of Michigan, Ann Arbor.
Surgery. 1992 Feb;111(2):169-76.
This study was designed to probe the hypothesis that oxygen-derived free radicals are involved in initiation of the no-reflow phenomenon. We developed a reproducible model of no reflow in the rat hind limb. Laser Doppler studies confirmed that the hind limbs perfused well after 2 or 4 hours of ischemia, but perfusion ceased in the first 10 minutes after 6 hours of ischemia. Venous blood samples and biopsy specimens of skin and muscle were taken after 2 and 4 hours of ischemia to study tissue injury. Blood samples were evaluated for xanthine oxidase (XO), xanthine dehydrogenase, and creatine phosphokinase (CPK) activities. Conjugated dienes and iodine 125-labeled albumin extravasation were quantified in tissue samples. Groups of animals were treated with inhibitors of XO (allopurinol), antioxidant enzymes (superoxide dismutase plus catalase), and free radical scavengers (dimethyl sulfoxide and dimethyl thiourea) to assess the roles of free radicals in ischemia-reperfusion injury in the hind limbs. After 4 hours of ischemia followed by reperfusion, plasma XO activity rose threefold over preischemia levels (p less than 0.05). Xanthine dehydrogenase activity did not change; conjugated diene levels in muscle rose twofold; CPK levels rose sixfold, and 125I albumin extravasation rose twofold (p less than 0.05). Pretreatment with the XO inhibitor allopurinol reduced XO activity to negligible levels and significantly attenuated conjugated diene levels, CPK levels, and albumin extravasation. Albumin extravasation was also significantly attenuated by pretreating animals with superoxide dismutase together with catalase, dimethyl thiourea, and dimethyl sulfoxide. In all animals pretreated with allopurinol or superoxide dismutase and catalase, reperfusion persisted after 6 hours of ischemia. These data suggest that, in ischemia followed by reperfusion, tissue injury is related to oxygen products derived from XO activity.
本研究旨在探讨氧衍生自由基参与无复流现象起始过程的假说。我们建立了大鼠后肢无复流的可重复性模型。激光多普勒研究证实，缺血2或4小时后后肢灌注良好，但缺血6小时后最初10分钟内灌注停止。在缺血2小时和4小时后采集静脉血样本以及皮肤和肌肉活检标本，以研究组织损伤。对血样进行黄嘌呤氧化酶（XO）、黄嘌呤脱氢酶和肌酸磷酸激酶（CPK）活性评估。对组织样本中的共轭二烯和碘125标记白蛋白外渗进行定量分析。对动物组给予XO抑制剂（别嘌呤醇）、抗氧化酶（超氧化物歧化酶加过氧化氢酶）和自由基清除剂（二甲亚砜和二甲基硫脲），以评估自由基在大鼠后肢缺血再灌注损伤中的作用。缺血4小时后再灌注，血浆XO活性比缺血前水平升高了三倍（p<0.05）。黄嘌呤脱氢酶活性未改变；肌肉中的共轭二烯水平升高了两倍；CPK水平升高了六倍，125I白蛋白外渗升高了两倍（p<0.05）。用XO抑制剂别嘌呤醇预处理可将XO活性降低至可忽略不计的水平，并显著减轻共轭二烯水平、CPK水平和白蛋白外渗。用超氧化物歧化酶与过氧化氢酶、二甲基硫脲和二甲亚砜预处理动物也可显著减轻白蛋白外渗。在所有用别嘌呤醇或超氧化物歧化酶和过氧化氢酶预处理的动物中，缺血6小时后仍持续存在再灌注。这些数据表明，在缺血后再灌注过程中，组织损伤与XO活性产生的氧产物有关。
