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 Ringer solution made hypertonic by the addition of glycerol or of the other several substances.
1. For about sixty minutes, for which the observation was made, features of resting and action potentials from single muscle fibres in 420mM glycerol Ringer solution were almost the same as those in normal Ringer solution.
2. The mechanical twitch responses of sartorius muscle immersed in glycerol Ringer solution were at first diminished and then restored with time elapsed. The most prominent restoration occurred in 420mM glycerol Ringer solution, and the maximum restored twitch tension of a single fibre, which attained to 50-60 minutes after exchanging the bathing solution for glycerol one, was 60-70 percent of that in normal Ringer solution.
3. In 420mM glycerol Ringer solution, the weight of sartorius muscle dropped to 74-82 percent of that in normal Ringer solution within a few minutes, and then the dropped value kept constant for about an hour.
4. The similar mechanical phenomenon was observed in rectus abdominis muscle but not in heart ventricle. It was also found in partially depolarized sartorius muscle stimulated by A. C. electric field.
5. The restoration of the mechanical twitch response did not occur in sartorius muscles under the condition of Ringer solutions made hypertonic by the addition of excess NaCl, mannitol, glucose, monoacetin and sucrose respectively, and the observable change was only 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.
6. From these results, the mechanism of the peculiar effect of glycerol was discussed in connection with the excitation-contraction coupling process of muscle.
