烧伤焦痂毒性物质提物D_1对大鼠肝线粒体呼吸链的损害

A study on the damages of a burn eschar extract to mitochondrial respiratory chain in the rat

本文报告烧伤焦痂提取物中可溶于有机溶剂组分Ｄ１对大鼠肝线粒体功能及呼吸链的损害作用。结果表明第３态呼吸受Ｄ１抑制，第４态受Ｄ１刺激而增高，耗氧率变化与Ｄ１用量之间存在着显著的量效关系。低剂量时耗氧率的改变缓慢，高剂量时耗氧率的变化急剧，这个转折点在Ｄ１浓度为１ｍｇ／ｍｌ处。氰化羰酰－３－氟苯腙（ＦＣＣＰ）／第４态耗氧率比值随Ｄ１浓度增加而下降，磷酸化位点１底物与位点２底物的实验结果相似，在Ｄ１浓度为１ｍｇ／ｍｌ处也存在一个比值下降坡度变化的转折点。ＦＣＣＰ／第４态耗氧率比值下降表示复合物Ⅰ～Ⅲ及Ⅱ～Ⅲ节段有损伤。与此相反，位点３底物实验中未见ＦＣＣＰ／第４态耗氧率比值变化，说明复合物Ⅳ无损伤。有关酶活力测定进一步证实上述呼吸链损伤的定位结果。受Ｄ１作用后，还原型辅酶Ⅰ（ＮＡＤＨ）：细胞色素ｃ还原酶与琥珀酸：细胞色素。还原酶活力均明显下降，但复合物Ⅰ中的ＮＡＤＨ脱氢酶与复合物Ⅱ中的琥珀酸脱氢酶活力却无改变，说明损伤的部位很可能在复合物Ⅲ即ｂｃ１ｃｏｍｐｌｅｘ处，有关的功能实验正在进行中。

The effects of substance D1,an extract from burn eschars,on hepatic mitochondrial respiratory function and the damages to the respiratory chain were studied in the rat.The rate of state 3 and state 4 respiration,the FCCP-stimulated respiratory rate,the respiratory control ratio,and the ratio between FCCP rate and state 4 rate were determined and the activities of NADH:cytochrome c reductase,succinate: cytochrome c reductase,NADH dehydrogenase and succinate dehydrogenase were measured.It was found that D1 inhibited state 3 respiratory but stimulated state 4 respiration. There was a dosage effect relationship between the dosage of D1 and the changes of the rate of Oxygen consumption. The turning point was at the D1 concentration of 1mg/ml.The ratio of FCCP-stimulated rate with state 4 rate was decreased when the dosage of D1 increased.The experimental results were similar if glutamate,malate or succinate was used.The turning point of the ratio decreasing gradient was at the D1 concentration of 1 mg/ml.The decrease of FCCP-stimulated rate and state 4 rate indicates that there are damages to the respiratory chain. Cytochrome oxidase,the terminal segment of the chain,was intact.Therefore,the damage might occur somewhere in complexes Ⅰ～Ⅲ and Ⅱ～Ⅲ.The activities of NADH:cytochrome c reductase and succinate:cytochrome c reductase were both markedly inhibited while those of NADH dehydrogenase and succinate dehydrogenase remained intact. These findings suggest further that the damage might occur in complex Ⅲ,the bc1 complex.