Effects of temperature on isometric contraction of rat muscle

¹ Department of Physiology and Biophysics, University of Louisville School of Medicine, Louisville, Kentucky

The effects of temperature on the basic characteristics of isometric contraction were studied in the triceps surae of white albino rats. The influences of tetanic fusion and Wedensky inhibition on tension development were analyzed. The results showed linear increase of maximal isometric tetanic tension and increase in the rate of rise and fall of twitch and tetanic isometric contractions with increase in temperature. Indirect stimulation produced somewhat lower tetanic tensions than direct stimulation. The optimal frequency of stimulation for maximal tetanic tension development was usually lower than the critical frequency of tetanic fusion. Reduction of tension by excessively high frequencies of stimulation, due to the Wedensky effect, was observed with indirect stimulation, and occurred at a lower frequency than the critical frequency of fusion.

Key Words: mammalian muscle • striated muscle • triceps surae • muscle cooling • critical frequency of fusion • optimal frequency of stimulation • Wedensky • contraction time • relaxation time • tetanus rise and fall

Submitted on January 17, 1964