DFP-induced elevation of strength-duration threshold in hen peripheral nerve.
Previous research has indicated that organophosphorus agents which induce a delayed neuropathy also elevate the strength-duration threshold during the progression of the neuropathy. To establish further the correlation between strength-duration changes and delayed neuropathy, the purpose of the present study was to investigate the biochemical and electrophysiological effects of two additional agents: diisopropylflourophosphate (DFP) and phosphonothioc acid, methyl-[2-(dimethylamino)-ethyl]O-ethyl ester (VX). DFP-treated hens exhibited clinical signs of toxicity at the time of electrophysiologic recording and biochemical analysis. DFP treatment also resulted in significantly elevated thresholds of the strength-duration curves of both the sciatic and tibial nerves. The VX-treated animals exhibited no clinical signs, despite aggressive dosing, and there were no significant changes in the electrophysiologic characteristics (conduction velocity, relative refractory period, strength-duration threshold) of either peripheral nerve. Acetylcholinesterase activities of the brain and skeletal muscle were significantly reduced in the VX- and DFP-treated hens, whereas creatine phosphokinase activities in these tissues were unaffected. These results are consistent with the view that elevation of the strength-duration threshold in peripheral nerves is among the earliest indicators of organophosphorus-induced delayed neuropathy.
Anderson
R J
RJ
Toxicology Program, School of Public Health, University of Michigan, Ann Arbor.
Robertson
D G
DG
Henderson
J D
JD
Wilson
B W
BW
D000110:Acetylcholinesterase / Q000378:metabolism; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002645:Chickens; D003402:Creatine Kinase / Q000378:metabolism; D005260:Female; D007531:Isoflurophate / Q000633:toxicity*; D009431:Neural Conduction / Q000187:drug effects; D009946:Organothiophosphorus Compounds / Q000633:toxicity; D010525:Peripheral Nerves / Q000187:drug effects* / Q000502:physiology
D000110:Acetylcholinesterase; D003402:Creatine Kinase; D007531:Isoflurophate; D009946:Organothiophosphorus Compounds; C009680:VX-agent