PHOSPHOTRIESTERASE - A PROMISING CANDIDATE FOR USE IN DETOXIFICATION OF ORGANOPHOSPHATES

The effect of phosphotriesterase (PTE) on cholinesterase (ChE) activit ies was studied with exposures to different organophosphates in mice. Paraoxon (PO) (1.0 mg/kg, ip) almost totally inhibited serum ChE activ ity. This activity, however, recovered to the normal level within 24 h r. The PTE pretreatment (16.8 U/animal, 2.5 mu g/10 g body wt, iv 10 m in before the organophosphate) accelerated this reactivation. The same phenomenon was also seen in vitro. In vitro with human serum, there w as only minimal reactivation of the inhibited ChE. PTE, however, react ivated it significantly. The PTE-pretreated mice (168 U/animal, 30 mu g/10 g body wt, iv) tolerated even 50 mg/kg of PO without showing any remarkable signs of intoxication. In PTE-untreated animals, however, P O doses as low as 1.0 and 1.5 mg/kg caused severe signs of poisoning. PTE (16.8 U/animal, 4 mu g/10 g body wt, iv) reduced the inhibition of brain and serum ChE activities after PO and diisopropyl fluorophospha te exposure. In sarin and soman intoxications, PTE decreased only slig htly the inhibition of ChE activities. The results indicate that PTE p retreatment given iv prevents the inhibition of ChE activities after c ertain organophosphates and it also hastens the recovery of activities after PO poisoning. (C) 1994 Society of Toxicology.