van der Wel H, Welling W
Institute of Pesticide Research, Wageningen, The Netherlands.
Ecotoxicol Environ Saf. 1989 Apr;17(2):205-15. doi: 10.1016/0147-6513(89)90039-0.
Acetylcholinesterase activity is a potential biochemical indicator of toxic stress in fish and a sensitive parameter for testing water for the presence of organophosphates. A number of methodological aspects regarding the determination of the in vivo effect of chlorpyrifos on acetylcholinesterase in guppies have been investigated. It was found that with acetylthiocholine as a substrate, the contribution of pseudocholinesterase to the total cholinesterase activity can be neglected. Protection of acetylcholinesterase of guppies exposed to chlorpyrifos from additional, artifactual in vitro enzyme inhibition during homogenization is necessary. Very low concentrations of acetone in the exposure medium, resulting from dilution of the stock solution of chlorpyrifos in acetone, can result in large decreases in the oxygen content of this medium. This may affect the uptake rate of the toxic compound and, thereby, cholinesterase inhibition. Very low, sublethal concentrations of chlorpyrifos result in high inhibition levels of acetylcholinesterase (80-90%) in guppies within 2 weeks of continuous exposure. Recovery of the enzyme activity occurs after the exposed animals are kept in clean medium for 4 days, but the rate of recovery is considerably lower than the rate of inhibition.
乙酰胆碱酯酶活性是鱼类中毒性应激的一个潜在生化指标，也是检测水中有机磷存在的一个敏感参数。关于毒死蜱对孔雀鱼体内乙酰胆碱酯酶影响的测定，已对许多方法学方面进行了研究。结果发现，以乙酰硫代胆碱为底物时，假性胆碱酯酶对总胆碱酯酶活性的贡献可忽略不计。有必要保护暴露于毒死蜱的孔雀鱼的乙酰胆碱酯酶，使其在匀浆过程中免受额外的、人为的体外酶抑制。由于毒死蜱丙酮储备液稀释导致暴露介质中丙酮浓度极低，可能会使该介质中的氧含量大幅降低。这可能会影响有毒化合物的摄取速率，从而影响胆碱酯酶抑制作用。极低的、亚致死浓度的毒死蜱在连续暴露2周内可导致孔雀鱼体内乙酰胆碱酯酶的高抑制水平（80 - 90%）。将暴露动物置于清洁介质中4天后，酶活性会恢复，但恢复速率远低于抑制速率。
