Flexor carpi radialis Muscle
Springer Online Journal Archives 1860-2000
Summary The mechanical activity of the isolatedflexor carpi radialis muscle (FCRM) of the mature male frog (Rana temporaria) was compared to that of thesartorius muscle. Muscles were stimulated directly by massive shocks at 20°C and isometric tension was recorded during single twitch, twitch series, long tetani and long tetanus series. Some groups of muscles were poisoned with IAA-N2 or FDNB. The FCRM showed a high resistance to fatigue during a tetanus series and a “fatigue contracture” during a twitch series. The rate of the tetanic tension rise was smaller by five to six times than in thesartorius muscle (0 to 50% P0) and the twitch/tetanus ratio was always very small. During continuous activity and after the blocking of recovery metabolic pathways, FCRM used its energetic stores two to three times slower than thesartorius muscle. These stores did not seem to be more important. The results indicate that the FCRM is not a “tonic” muscle but, quite possibly, is composed of several types of fibre like many other frog muscles. However, some characteristics of mechanical response cannot be explained by the common classification into two types of fibre.
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