Protection of human muscle acetylcholinesterase from soman by pyridostigmine bromide.

Introduction: Pretreatment with pyridostigmine bromide (PB) of human intercostal muscle fibers exposed to the irreversible acetylcholinesterase (AChE) inhibitor soman was investigated. Methods: Muscles were pretreated with 3 × 10−6 M PB or saline for 20 minutes, then exposed to 10−7 M soman for 10 minutes. Results: AChE of muscles treated with soman alone was inhibited >95%. In contrast, PB pretreatment of soman-exposed bundles protected 20% of AChE activity. AChE of bundles exposed to PB alone recovered after 4 hours, but bundles exposed to both PB and soman did not. Soman-induced reduction of resting membrane potentials and increment of amplitudes and decay times of miniature endplate potentials (MEPPs) were partially corrected by PB pretreatment. Conclusions: In vitro pretreatment of human muscles with PB protected up to 20% of muscle AChE and ameliorated some deleterious effects on endplate physiology induced by soman. Muscle Nerve 43: 591–595, 2011