Protection of organophosphate-inactivated esterases with phosphotriesterase

The protective effect of phosphotriesterase (PTE) on cholinesterase (ChE) and carboxylesterase (CaE) activities was studied in mice. The PTE pretreatment (120 U/g body wt, 9.6 micrograms/g body wt) given i.v. 10 min before diisopropyl fluorophosphate, sarin, or soman variably prevented ChE inhibition in erythrocytes and plasma and CaE in plasma. PTE also protected the brain and lung ChEs against inactivation by organophosphates (OPs). The recovery of the enzymes was dependent on the OP used. Postexposure therapy with PTE, given 1.5 hr after paraoxon, also prevented ChE inhibition in erythrocytes, brain, and lung 24 hr after exposure. The distribution studies with [125I]PTE showed that PTE does not markedly gain access into the central nervous system.