[Anticholinesterase activity and delayed neurotoxic effects of tabun in hens]

Organophosphorus compounds can cause two distinct toxic effects: acute, which are the consequence of acetylcholinesterase (AChE) inhibition and delayed neuropathy being inhibited by inhibition of neuropathy target esterase (NTE) with first signs (ataxia, paralysis) appearing 7-20 days after intoxication. The purpose of this study was to examine interaction of tabun with AChE and NTE and potential neuropathic effects of the compound in vivo. Tabun was more potent inhibitor reacting with more affinity with AChE than NTE of hen brain. The rate of aging of tabun-inhibited AChE was slow (t/2 = 50 hours) while it occurred very rapidly on tabun-inhibited NTE (t/2 = 6.5. min). Experiments in vivo have shown that even a high dose of tabun (12 mg/kg, 120 LD50), given with antidotes, which inhibited 67% of NTE activity did not initiate delayed neuropathic effects. It is concluded that there appears to be no risk for development of delayed neuropathy in tabun poisonings.