THE EXCITATION-CONTRACTION COUPLING OF THE SKELETAL MUSCLE AND THE ‘GLYCEROL EFFECT’

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Abstract
In order to clarify the mechanism of E-C coupling process of the muscle, electrical and mechanical responses to the electrical stimulation and the relationship between their changes and the muscle weight were investigated in hypertonic Ringer solution. For about sixty minutes, resting and action potentials from single muscle fibers in 420mM glycerol Ringer solution were almost the same as those in normal Ringer solution The mechanical twitch responses of sartorius muscle immersed in glycerol Ringer solution were at first diminished and then restored with time. In 420 mM glycerol Ringer solution, the weight of sartorius muscle dropped to 74-82% of that in normal Ringer solution within a few minutes, and then remained constant for about an hour. The restoration of the mechanical twitch response did not occur in sartorius muscle when Ringer solutions were made hypertonic by the addition of excess NaCl, mannitol, glucose, monoacetin and sucrose respectively. The only observable change was a gradual diminution of mechanical twitch response. In the case of urea Ringer solution, however, the restoration appeared, though the grade was considerably less than that in glycerol.