MECHANISM OF THE RESTORATION OF INTRACELLULAR CATION LEVEL IN THE MUSCLE IMMERSED WITH SUCROSE SOLUTION

Abstract

In the sartorius muscles isolated from the frog and toad, the inward cumulative movement of cations which had been reduced by soaking in isotonic sucrose solution was investigated under various experimental conditions.1. The cationic inward movement during the recovery is uphill for K ion and downhill for Na ion. The restoration of internal Na takes place more rapidly than that of internal K. The reaccumulation of internal Na in Ringer, saline and sometimes K free Ringer shows the saturation at around the normal level and causes no continuously increasing entry of Na ion. The fact suggests that a regulating process for internal Na level, which does not cooperate with external K, is revived by the passively inward diffusion of Na ion and it determins the amount of internal K accumulation by influencing the movement of K ion.2. No close interrelationship was observed between the cumulative pattern of internal Na and that of internal K especially at the beginning of the recovery. However, K outflux is inhibited even in the K free recovery solution when internal Na is restored to a certain critical level and is maintained at this level. The internal K accumulates actively under K-present condition when the entry of permeable cation such as Na or choline takes place. When the muscle fails to keep internal Na at this fixed level the decrease in internal K occurs gradually in the recovery solution.