THE INFLUENCE OF TEMPERATURE ON THE ACTION OF DIGITOXIN AND POTASSIUM ON STRIATED MUSCLE

¹ From the Department of Pharmacology, Cornell University Medical College, New York

1. Following the exposure of the frog double sartorius preparation to Ringer's solution with digitoxin or Ringer's solution with potassium excess a gradual reduction in twitch tension ensues.

2. The time for the development of 50 per cent reduction in twitch tension in digitoxin Ringer's solution is altered by temperature—a Q₁₀ of about 2 exists. The time for development of half tension for preparations treated with potassium excess Ringer's is essentially unaltered by temperature difference of 10 degrees C.

3. From the available literature and the data presented, it seems reasonable to postulate the mode of action of the glycosides as follows: Chemical union of the glycoside with a cell constituent (as evidenced by a high Q₁₀) followed by a decrease in the capacity of the cell to hold potassium which escapes into the intercellular spaces, resulting in an excess of potassium ions surrounding the cells and a reduction inside the cell. The latter ionic phase is influenced very little by temperature.