Effect of butanedione monoxime on the contractility of guinea pig ileum and on the electrophysiological activity of myenteric S-type neurones.

2,3-Butanedione monoxime (BDM) has demonstrated protective effects on isolated cardiac tissues, and on smooth muscle but its mechanism of action is not fully understood. To simultaneously study the effect of BDM on muscle contractility and on neuronal activity, the effect of BDM was tested in the contractile force of myenteric plexus-longitudinal muscle strips and in electrophysiological activity of myenteric S-type neurones of guinea pig ileum. BDM reduces, in a dose-dependent manner, the force of the spontaneous motility and the contractions induced by acetylcholine, bethanechol and electrical stimulation. The same BDM concentrations depolarize the neuronal membrane and reduce the rate of evoked firing. The effect of BDM can be attributed to a direct effect on the smooth muscle and to modifications of the neuronal activity.