[Stimulating effects of sodium dantrolene on smooth muscle organs]

The effects of sodium dantrolene (DaNa) a calcium antagonist specifically acting on skeletal muscles were evaluated on the spontaneous contractions of ileum, uterine horns and longitudinal strips of oesophageal smooth muscle, in vitro. DaNa (1,81 to 15 micrograms/ml) caused a reversible dose-related increase of the spontaneous contractions of the three organs. DaNa (15 micrograms/ml) caused a 60 +/- 3% increase of the ileum spontaneous tone, and caused a 57 +/- 3% increase in the frequency of the spontaneous contractions of the uterus. The stimulatory effect of DaNa on the uterine musculature was not antagonized by atropine, methysergid or indomethacin. In the oesophagus the maximum increase of the spontaneous tone and contractions (65 +/- 2%), was due to 3,7 micrograms/ml perfusion of DaNa. This effect was antagonized by nifedipine.