Inhibition by Potassium of the Mechanical Responses of Frog Muscles at Low Temperature

Abstract

Csapo and Wilkie¹ reported a curious effect of temperature on the twitch tension in the frog's sartorius muscles, as influenced by the action of 24 mM potassium chloride. The onset of the fall of tension development and the depolarization were delayed by lowering the temperature from 23° to 2° C, corresponding to a Q₁₀ of 1.2–1.3. On the other hand, the rate of recovery, when normal Ringer solution was replaced, was very much reduced at lower temperature. However, if the recovering muscle were suddenly warmed again, the twitch tension recovered immediately. Grieve² has shown that, when recovery was delayed, it was due to delayed re-polarization. If chloride were replaced by the impermeant methyl sulphate, then there was no delay in re-polarization that could not be accounted for by diffusion in the interspaces.