Ghanayem B I
National Institute of Environmental Health Sciences, National Toxicology Program/Systemic Toxicology Branch, Research Triangle Park, NC 27709.
Biochem Pharmacol. 1989 May 15;38(10):1679-84. doi: 10.1016/0006-2952(89)90317-1.
Recent work in this laboratory indicated that 2-butoxyethanol (BE) causes acute hemolytic anemia in rats, and activation of BE to butoxyacetic acid (BAA), presumably through the intermediate 2-butoxyacetaldehyde (BAL), is a prerequisite for development of hematotoxicity. In the present studies, the effects of BE and its metabolites, BAL and BAA, on erythrocytes from rats and humans were investigated in vitro. Incubation of BE (up to 10 mM) with blood from male F344 rats caused no hemolysis and resulted in no metabolic alteration of BE. Further, addition of alcohol and aldehyde dehydrogenases, with their co-factors, to the incubation mixture failed to alter BE or its effect. At 20 mM, BE caused significant (P less than or equal to 0.05) hemolysis of rat erythrocytes accompanied by a significant (P less than or equal to 0.05) decrease in hematocrit (HCT). In contrast, incubation of BAL or BAA with rat blood caused time- and concentration-dependent swelling of red blood cells followed by hemolysis; however, BAA was significantly more efficacious than BAL. Addition of aldehyde dehydrogenase and its co-factors significantly (P less than or equal to 0.05) potentiated the effect of BAL on rat erythrocytes. Further in vitro investigation of the cellular mechanisms involved in the hemolytic effect revealed that incubation of rat blood with BAA or BAL caused a time- and concentration-dependent decrease in blood ATP concentration. As observed with the hemolytic effects, the decrease in blood ATP was significantly (P less than or equal to 0.05) greater with BAA than with BAl and was not induced by BE. Further, BAA caused no significant changes in the concentration of reduced glutathione and glucose-6-phosphate dehydrogenase in rat erythrocytes. Assessment of human sensitivity by incubation of human blood with BAA showed minimal swelling or hemolysis of erythrocytes with minimal decline in blood ATP levels at BAA concentrations several-fold higher than required to cause complete hemolysis of rat erythrocytes. In summary, the current studies confirm that the hemolytic effect of BE can be attributed primarily to its metabolite BAA, that hemolysis of rat erythrocytes by BAA or BAL is preceded by swelling and ATP depletion, suggesting that the erythrocyte membrane is the most likely target, and, finally, that human erythrocytes are comparatively insensitive to the hemolytic effects of BAA in vitro.
本实验室最近的研究表明，2-丁氧基乙醇（BE）可导致大鼠急性溶血性贫血，并且BE激活生成丁氧基乙酸（BAA）（可能是通过中间产物2-丁氧基乙醛（BAL））是产生血液毒性的前提条件。在本研究中，对BE及其代谢产物BAL和BAA在体外对大鼠和人类红细胞的影响进行了研究。将BE（浓度高达10 mM）与雄性F344大鼠的血液一起孵育未引起溶血，且BE未发生代谢改变。此外，在孵育混合物中添加醇脱氢酶和醛脱氢酶及其辅酶，未能改变BE或其作用。在20 mM时，BE导致大鼠红细胞显著（P≤0.05）溶血，同时血细胞比容（HCT）显著（P≤0.05）降低。相比之下，将BAL或BAA与大鼠血液一起孵育会导致红细胞出现时间和浓度依赖性肿胀，随后发生溶血；然而，BAA的效力明显高于BAL。添加醛脱氢酶及其辅酶显著（P≤0.05）增强了BAL对大鼠红细胞的作用。对溶血作用所涉及的细胞机制进行的进一步体外研究表明，将大鼠血液与BAA或BAL一起孵育会导致血液ATP浓度出现时间和浓度依赖性降低。正如在溶血作用中观察到的那样，BAA导致的血液ATP降低显著（P≤0.05）大于BAL，且BE不会诱导这种降低。此外，BAA未引起大鼠红细胞中还原型谷胱甘肽和葡萄糖-6-磷酸脱氢酶浓度的显著变化。通过将人血与BAA一起孵育来评估人体敏感性，结果显示在BAA浓度比导致大鼠红细胞完全溶血所需浓度高几倍的情况下，红细胞仅有轻微肿胀或溶血，血液ATP水平仅有轻微下降。总之，当前研究证实，BE的溶血作用主要可归因于其代谢产物BAA，BAA或BAL导致大鼠红细胞溶血之前会出现肿胀和ATP耗竭，这表明红细胞膜最可能是作用靶点，最后，人红细胞在体外对BAA的溶血作用相对不敏感。
