Capacity of Skeletal Muscle of Castrated Male Rats to Sustain Work Output

Abstract

A comparison has been made of normal and castrated male rats in respect to the capacity of the gastrocnemius muscle to perform work when made to contract by faradic stimulation.

Albino male rats were closely matched into 12 pairs on a basis of body weight and one animal of each pair was castrated on the twenty-first day following birth. The castrated and control animals were maintained under uniform conditions. Each rat was prepared for the work test on the first day that its body weight reached 180 g. The animal was anesthetized with phenobarbital sodium; its gastrocnemius muscle was weighted with 100 g and was stimulated directly to contract 3 times per second until the “fatigue” of the muscle or for a maximum of 120 hours. The amount of work performed was recorded automatically. Each rat received 5 cc of physiologic saline solution by subcutaneous injection every 12 hours. A detailed description of the apparatus and procedures used has been presented.

The data on averages and range for 12 pairs of rats are summarized in Table I. No inferiority of the castrated male rats to sustain work was observed in this experiment. This finding does not agree with the experimental results of Gans and Hoskins, 1 who used a somewhat similar method for the study of work performance in castrated rats. The times for continuation of muscular contractions and the values for total work for both normal and castrated rats were much smaller in their experiment than in the present one. Heron, Hales, and Ingle have discussed some of the important differences between the methods used by Gans and Hoskins and the method described by themselves, which I have used in this experiment.