A TECHNIQUE FOR OBTAINING AND RECORDING ISOMETRIC CONTRACTIONS OF MAMMALIAN SKELETAL MUSCLES IN SITU

Abstract

A technique is described whereby isometric contractions of dogs'' muscles (gracilis) stimulated in situ through their nerves are recorded by means of a torsion wire myograph of special design. Periods of activity composed of tetanic contractions of 0.5 sec. duration at a rate of 50 per min., show a progressive decrease in tension development either from the first or after about a dozen contractions. The trend of tension development is either toward a "steady state" in which the muscle continues to develop an approximately constant tension during a long series of contractions or toward a condition of "exhaustion" in which not enough tension is developed to be measured on the tracing.