Mechanism of soman-induced contractions in canine tracheal smooth muscle. (Reannouncement with new availability information)
The actions of the irreversible organophosphorus cholinesterase (ChE) inhibitor soman were investigated on canine trachea smooth muscle in vitro. Concentrations of soman > or - 1 nM increased the amplitude and decay of contractions elicited by electric field stimulation. The effect on decay showed a marked dependence on stimulation frequency, undergoing a 2.4-fold increase between 3 and 60 Hz. Soman also potentiated tensions due to bath applied acetylcholine (ACh). Little or no potentiation was observed for contractions elicited by carbamylcholine, an agonist that is not hydrolyzed by ChE. Concentration of soman > or - 3 nM led to the appearance of sustained contractures. These contractures developed with a delayed onset and were well correlated with ChE activity. Alkylation of muscarinic receptors by propylbenzilylcholine mustard antagonized the actions of soman on both spontaneous and electrically-evoked muscle contractions. The results are consistent with a mechanism in which the toxic actions of soman are mediated by accumulation of neurally-released ACh secondary to inhibition of ChE activity. An important factor in this accumulation is suggested to be the buffering effect of the muscarinic receptors on the efflux of ACh from the neuroeffector junction. Tracheal smooth muscle, Cholinesterase inhibitors, Muscarinic receptor, Soman, Organophosphate.
- Research Organization:
- Army Medical Research Inst. of Chemical Defense, Aberdeen Proving Ground, MD (United States)
- OSTI ID:
- 166872
- Report Number(s):
- AD-A-250885/1/XAB; USAMRICD-P-89-046; TRN: 53520650
- Resource Relation:
- Other Information: PBD: 1992
- Country of Publication:
- United States
- Language:
- English
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