Differential response of dog and pig tracheal smooth muscle to the acetylcholinesterase inhibitor soman

The effect of the acetylcholinesterase inhibitor soman on tracheal smooth muscle (TSM) from the dog and pig was studied. In response to soman, tracheal ring preparations contract more and the resting tension for TSM preparations is higher for the dog compared with the pig. Tension induced by electrical field stimulation (EFS) and the half-time of EFS-train induced contractions have a similar dependence on soman exposure in both dog and pig TSM. These results suggest that the basal acetylcholine secretion or leakage within the TSM nerve terminal is probably higher for the dog compared with the pig.