| 8343987 |
Gupta RC, Dettbarn WD: Role of carboxylesterases in the prevention and potentiation of N-methylcarbamate toxicity. Chem Biol Interact. 1993 Jun;87(1-3):295-303.
Pretreatment of rats with iso-OMPA one hour prior to each of the N-methylcarbamate insecticides, carbofuran, propoxur, or aldicarb, potentiated the toxicity of these carbamates threefold. None of these compounds alone in the dosage used produced toxic signs; however, carboxylesterase (CarbE) activity in a variety of organs including brain, muscle, liver, and plasma was significantly reduced, while acetylcholinesterase (AChE) activity was unchanged. Significant inhibition of AChE was observed after the combination of tetraisopropylpyrophosphoramide (iso-OMPA) with each one of these N-methylcarbamates. It is suggested that CarbEs are more sensitive than AChE to these N-methylcarbamates and inhibition of CarbE by iso-OMPA raises the concentration of N-methylcarbamates available to inhibit AChE resulting in increased toxicity. Other N-methylcarbamates such as physostigmine do not inhibit CarbE, nor are their toxicities potentiated by iso-OMPA. |
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