Relationship between Changes in Muscle Volume and Muscle Action Potential

Journal/Book: (Reprinted from Nature Vol. 195 No. 4838 p. 290 only July 21 1962). 1962;

Abstract: THE method which was developed for measuring small rapid changes in volume occurring in a muscle during a single twitch1 has been applied to the case of a frog sartorius muscle immersed in hypertonic Ringer's solution. As reported by various authors one of the principal effects of hypertonic Ringer's solution on a muscle is to eliminate the twitch tension on stimulation but not to interfere with the propagation of the muscle action potential. This provides a method of determining whether or not the previously reported muscle volume changes are a direct consequence of the action potential and are thus not connected with contraction as such. The method used to measure these volume changes has been described elsewhere2. In this experiment the same method was used except after determining the changes in volume in normal Ringer's solution hypertonic Ringer's solution (2·5 times the regular concentration) was added to the muscle chamber. Since this addition took approximately 30 sec. the changes in volume were not measured until this point. Thirty seconds after the addition of the 2·5 Ringer's solution the muscle was stimulated by a single stimulus and the volume changes recorded. After the addition of hypertonic Ringer's solution to the muscle the magnitude of the tension slowly decreases. In addition to the decrease in magnitude of tension the rate of development of tension is greatly prolonged. After the muscle has been in the hypertonic Ringer's solution for approximately 15 min. no tension can be developed on twitch stimulation. ... schö

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