Effects of Hypoxia and Environmental Agents on Renal Tubules with a Scope of Combined Effect

当我们评估多种药物在实验动物中的联合作用以外推到人类时，关于它们在活体器官中相互作用机制的数据显然是有帮助的。因此，我们已经开发了在体扫描反射分光光度法和在体表面荧光法，用于实时观察细胞内的生化变化，以便将该技术应用于环境和职业毒理学研究在兔近端肾小管和灌流大鼠肾脏。测定乳酸脱氢酶（LDH）的释放作为质膜损伤的指标。测定细胞内钾、钙含量。钙含量略有下降，在缺氧，但增加了四倍，在严重缺氧。缺氧或低氧时呼吸功能损害的程度相同，表明钙积累与呼吸功能损害无关。细胞外Ca ~（2+）降低至2.5<micrn>时，缺氧时LDH释放量明显减少，提示缺氧时质膜损伤可能与细胞内游离Ca ~（2+）增加有关。在肾小管上皮细胞悬液中观察了有机溶剂对细胞的损伤作用，并在一定范围内观察了有机溶剂的联合作用。本研究中所用的有机溶剂在低浓度时增加了肾小管细胞的耗氧量，而在相对高的浓度时则降低了肾小管细胞的耗氧量。本研究将小鼠离体细胞悬液和肾脏灌流液作为评价多种环境因子联合作用的实验模型。

When we assess the combined effect of plural agents in the experimental animals for extrapolation to human, the data eliciting mechanisms about their interactions in the living organ are obviously helpful. Thus, we have developed in vivo scanning reflectance spectrophotometry and in vivo surface fluorometry for this purpose of the real-time observation of intracellular biochemical changes in order to apply the techniques to the studies in environmental and occupational toxicology in rabbit proximal renal tubules and in perfused rat kidney. The release of lactate dehydrogenase (LDH) was measured as an index of plasma membrane damage. The cellular contents of K and Ca were also measured. Ca content decreased slightly during anoxia, but increased up to fourfold during severe hypoxia. The degree of respiratory impairment was identical during anoxia or hypoxia, suggesting that Ca accumulation was not associated with the impairment. Decreasing the extracellutar Ca to 2.5 <micrn> decreased LDH release significantly during anoxia, suggesting that plasma membrane damage during anoxia may be associated with increased intracellular free Ca. Effects of organic solvents on cell injury were assessed in the tubular cell supsension with a scope of combined effect. The organic solvents employed in this study increased oxygen consumption in the tubular cells at its low concentrations, whereas they decreased the oxygen consuption at relatively high concentrations. Both bubular cell suspension and perfused kindney in the present study were considered as an experimental model for assessment of combined effects of plural environmental agents.