许多anurans具有出色的脱水耐受性,可以承受高达50-60%的体内水分损失。严重脱水的影响之一是由于血液体积减少和粘度增加导致的循环损害,导致器官缺氧.补液情况,因此,涉及组织的复氧,可能包括类似于哺乳动物器官缺血后再灌注损伤的氧化应激元素。内源性针对氧自由基的防御在豹蛙对严重脱水的耐受性中的作用,RanaPipiens,通过监测对照的腿部肌肉和肝脏中抗氧化酶和谷胱甘肽水平(还原的GSH和氧化的GSSG)的活性进行研究,50%-脱水,和充分补充水分的青蛙。肌肉过氧化氢酶和肝脏谷胱甘肽过氧化物酶的最大活性,每毫克可溶性蛋白质测量,显著增加了52%和74%,分别,脱水后,肌肉超氧化物歧化酶和谷胱甘肽还原酶活性反应相反,下降了32%和35%,分别。完全再水合后,酶活性恢复到对照水平。肝脏GSH和GSSG在补液过程早期增加(恢复总体内水分的30%),但完全恢复后恢复到控制水平。对于肝脏GSSG观察到类似的趋势。脱水过程中抗氧化剂对过氧化物的防御能力的提高可以为再水化过程中的缺氧后氧自由基应激提供保护。的确,分析一种脂质过氧化产物,硫代巴比妥酸反应性物质,在青蛙组织中,在脱水/复水周期中没有氧化应激的迹象。
Many anurans have excellent dehydration tolerance that allows endurance of the loss of up to 50-60% of total body water. One of the effects of severe dehydration is circulatory impairment due the reduced volume and increased viscosity of blood, which leads to organ hypoxia. The rehydration situation, therefore, involves a reoxygenation of tissues that may include elements of oxidative stress that resemble the injury in post-ischemic reperfusion of mammalian organs. The role of endogenous defenses against oxygen radicals in the tolerance of severe dehydration by leopard frogs, Rana pipiens, was investigated by monitoring the activities of antioxidant enzymes and glutathione levels (reduced GSH and oxidized GSSG) in leg muscle and liver of control, 50%-dehydrated, and fully rehydrated frogs. The maximal activities of muscle catalase and liver glutathione peroxidase, measured per mg soluble protein, increased significantly by 52 and 74%, respectively, after dehydration whereas muscle superoxide dismutase and glutathione reductase activities responded oppositely, decreasing by 32 and 35%, respectively. Enzyme activities returned to control levels after full rehydration. Hepatic GSH and GSSG increased early in the rehydration process (30% recovery of total body water), but returned to control levels after full recovery. A similar trend was observed for liver GSSG. The elevation of antioxidant defenses against peroxides during dehydration could provide protection against post-hypoxic oxyradical stress during rehydration. Indeed, analysis of one product of lipid peroxidation, thiobarbituric acid reactive substances, in frog tissues gave no indication of oxidative stress during the dehydration/rehydration cycle.