THE EFFECTS OF MULTIPLE LOW-DOSES OF ORGANOPHOSPHATES ON TARGET ENZYMES IN BRAIN AND DIAPHRAGM IN THE MOUSE

1 Multiple low doses of the direct acting organophosphates, ecothiopat e, paraoxon and mipafox produced persistent and additive inhibition of diaphragm acetylcholinesterase. Paraoxon and mipafox had similar effe cts on brain acetylcholinesterase. There was greater recovery from inh ibition between doses for paraoxon and ecothiopate than for mipafox. 2 Ecothiopate did not inhibit brain acetylcholinesterase but there was a small increase in activity. 3 Mipafox also had a cumulative inhibito ry effect on brain neuropathy target esterase. 4 These results have pa rticular implication for the use of multiple low doses of organophosph ates occupationally by man.