A comparison of the effects of sodium thiocyanate and dantrolene sodium on a mammalian isolated skeletal muscle.

1 A combination of electrical and pharmacological stimulation has been used to compare the effects of sodium thiocyanate and dantrolene sodium on the excitation-contraction coupling (ECC) mechanism of the mouse soleus muscle. 2 Thiocyanate prolonged the 'active state' after electrical stimulation and increased the response to 8 mM caffeine and 80 mM KCl. Dantrolene had an opposite effect to thiocyanate on all the indices studied. 3 It is concluded that the mechanism of action of dantrolene is by inhibition of the release of the calcium ions involved in the ECC mechanism, probably at the level of the transverse tubules.