Abstract

Effect of skeletal muscular relaxant, dantrolene, on isolated longitudinal smooth muscle of mouse ileum of which contractions were induced by 10-6 M of acetylcholine (ACh) was investigated. Studies were performed in Tyrode solution. The first ACh-induced (10-6 M) contraction was accepted as the control. Dantrolene was directly added to the organ bath and a second ACh-induced contraction was obtained after 15-minutes standing interval. Responses of two contractions were compared and the inhibition percentage was determined. Dantrolene was studied in five different concentrations (10-10 -10-6 M). 10-6 M of dantrolene significantly reduced the ACh-induced contractions of mouse ileum. ACh-induced contraction in isolated ileal longitudinal smooth muscle of mouse is mediated by influx of extracellular calcium. Dantrolene inhibits calcium channel in smooth muscle cell membrane. Therefore ACh-induced contractions were prevented by dantrolene.