Abstract
A newly synthesized drug, SX-284, depressed the twitch response of the ileum from guinea pig to electrical stimulation at 0.1 Hz. SX-284 proved to be almost as active as atropine on electrically stimulated ileum. The responses of guinea pig ileum to nicotine and serotonin were also inhibited by SX-284. However, SX-284 did not influence the release of transmitters from the motor, sympathetic, nonadrenergic inhibitory, noncholinergic excitatory nerves, and responses of various smooth muscles mediated through drug receptors, and at these doses, SX-284 inhibited the release of acetylcholine from the vagus nerve. These facts indicate that SX-284 specifically inhibits the acetylcholine release from the vagus nerve. Furthermore, spontaneous movement of the guinea pig ileum was dose-dependently depressed by SX-284. The potency ratio for SX-284 relative to atropine was 1.7.
