DIFFERENTIAL RESPONSE OF DOG AND PIG TRACHEAL SMOOTH-MUSCLE TO THE ACETYLCHOLINESTERASE INHIBITOR SOMAN

The effect of the acetylcholinesterase inhibitor soman on tracheal smo oth muscle (TSM) from the dog and pig was studied. In response to soma n, tracheal ring preparations contract more and the resting tension fo r TSM preparations is higher for the dog compared with the pig. Tensio n induced by electrical field stimulation (EFS) and the half-time of E FS-train induced contractions have a similar dependence on soman expos ure in both dog and pig TSM. These results suggest that the basal acet ycholine secretion or leakage within the TSM nerve terminal is probabl y higher for the dog compared with the pig.