The Inhibition of Human Blood Cholinesterase by Organophosphorus Compounds and the Reactivation by PAM (I)

When six organophosphorus compounds of P=S type (Parathion, Methylparathion, Malathon, Ekatin, Baycid and Sumithion) were treated with the oxidative reagent (bromine water), the inhibition of cholinesterase activity by these phosphorus compounds was markedly increased. Similar tendency was found in the case of thiol and sulfoxide type compounds. When these oxidized organophosphorus compounds were present, the reactivation rate of cholinesterase activity by PAM was elevated significantly. In contrast to these inhibitors dimethoate did not show the increased inhibition of cholinesterase activity by the oxidative treatment and in this case the effectiveness of PAM was also unchanged.