Hussain M A, Mohamad R B, Oloffs P C
J Environ Sci Health B. 1985 Feb;20(1):129-47. doi: 10.1080/03601238509372472.
The toxicity of acephate to four species of aquatic insects, as well as the metabolism and cholinesterase-inhibiting properties of the chemical in the rat were studied. The results indicated that mayfly larvae were very sensitive to the toxic effects of acephate, whereas larvae of the stonefly, damselfly and mosquito were much less sensitive. In the rat, orally-administered acephate was rapidly absorbed from the intestines and severely inhibited the cholinesterases in the blood and brain. The enzymes began to recover after 24 hours, while the chemical was completely eliminated within three days. The amount of methamidophos observed in the liver was extremely low. The cholinesterase-inhibiting properties of acephate and methamidophos were compared in vitro to that of paraoxon, a known strong anticholinesterase. Enzymes from four vertebrates were used. In all cases, except one, acephate was found to be six orders of magnitude weaker than paraoxon, whereas methamidophos was three orders weaker. Trout brain cholinesterase was the exception; it was as sensitive to paraoxon as it was to methamidophos. Finally, four cholinesterases were inhibited with methamidophos, and their ability to reactivate spontaneously or to recover by induction with pyridine aldoxime methiodide (PAM) in vitro were determined. The results suggested that methamidophos-inhibited cholinesterases did not reactivate spontaneously; instead the enzymes remained inhibited either in a phosphorylated or an aged state. The significance of these results are discussed in relation to the use of acephate for forest insect pests.
研究了乙酰甲胺磷对四种水生昆虫的毒性，以及该化学品在大鼠体内的代谢和胆碱酯酶抑制特性。结果表明，蜉蝣幼虫对乙酰甲胺磷的毒性作用非常敏感，而石蝇、豆娘和蚊子的幼虫则不太敏感。在大鼠中，口服的乙酰甲胺磷从肠道迅速吸收，并严重抑制血液和大脑中的胆碱酯酶。这些酶在24小时后开始恢复，而该化学品在三天内被完全清除。在肝脏中观察到的甲胺磷含量极低。将乙酰甲胺磷和甲胺磷在体外对胆碱酯酶的抑制特性与已知的强抗胆碱酯酶对氧磷进行了比较。使用了四种脊椎动物的酶。在所有情况下，除了一种情况外，发现乙酰甲胺磷比对氧磷弱六个数量级，而甲胺磷比其弱三个数量级。鳟鱼脑胆碱酯酶是个例外；它对对氧磷和甲胺磷的敏感性相同。最后，用甲胺磷抑制了四种胆碱酯酶，并测定了它们在体外自发重新激活或通过吡啶醛肟甲基碘（PAM）诱导恢复的能力。结果表明，甲胺磷抑制的胆碱酯酶不会自发重新激活；相反，这些酶要么以磷酸化状态，要么以老化状态保持被抑制。结合乙酰甲胺磷用于森林害虫防治对这些结果的意义进行了讨论。
