ACETYLCHOLINE IN PERIPLANETA AMERICANA L.: IV. THE SIGNIFICANCE OF ESTERASE INHIBITION IN INTOXICATION, ACETYLCHOLINE LEVELS, AND NERVOUS CONDUCTION

Abstract

Inhibition of ali-esterase (ALiE) of roaches by injections of tri-ortho-cresyl phosphate (TOCP) did not result in organophosphorus intoxication. Acetylcholinesterase (AChE) was not inhibited. Topical application of either tetraethylpyrophosphate (TEPP) or O,O-diethyl O-p-nitrophenyl phosphorothioate (parathion) to roaches treated with TOCP resulted in poisoning, inhibition of AChE, increases in the amount of acetylcholine (ACh), and disturbances in electrical nervous activity. Similar results were found for roaches treated only with either TEPP or parathion, but prostration was achieved more quickly in roaches first treated with TOCP, suggesting that TOCP treatment potentiated TEPP and parathion poisoning. Studies of electrical nervous activity in roaches showed that nervous conduction was not interfered with by ALiE inhibition. Synaptic nervous transmission was disrupted by inhibition of AChE with TEPP. Axonic nervous transmission was unimpaired although AChE was found to be inhibited.