Cordycepin depresses the skeletal muscle contraction of toad gastrocnemius muscle involving Ca2+-dependent mechanisms

AbstractThis study was carried out to investigate the modulation effect of cordycepin on the skeletal muscle contractile performance and its potential mechanisms involving interaction between cordycepin and Ca2+ by electrical field stimulation. Results showed that cordycepin (50 mg L−1) significantly decreased the muscle contractile response reversibly. Cordycepin also produced a rightward shift of the contractile amplitude–stimulation intensity relationship. However, the most noticeable result was that the maximum amplitude of the muscle contractile force was significantly increased under cordycepin application (119 ± 5·6% of control). This result suggests that the skeletal muscle contractile function and muscle physical fitness to the external stimulation were improved by the decreased response sensitivity in the presence of cordycepin. However, these improved effects of cordycepin on muscle physical performance were diminished in Ca2+-free medium or in the presence of all Ca2+ channels blocker (0·4 mM ...