Some Factors Affecting the Time Course of the Recovery of Contracture Ability Following a Potassium Contracture in Frog Striated Muscle

The recovery rate of contracture ability after a K contracture was shown to be initially dependent upon the rate of repolarization and later to be dependent upon a process which was sensitive to concentration and temperature changes in a manner consistent with chemical binding. It was shown qualitatively that repolarization did not depend on the presence of external calcium and the second process was studied by allowing the muscle to repolarize for 2 minutes in calcium-free solution following a K contracture. Recovery after this procedure was speeded by decreasing either the concentration of potassium in the contracture solution or its temperature and was slowed by either decreasing the calcium concentration of the recovery solution or its temperature or by increasing the duration of the exposure to potassium.