On the Silent Period and Golgi Tendon Organs of the Soleus Muscle of the Cat

Abstract

Abstract The silent period in the soleus during twitch contractions has been studied in intercollicularly decerebrated cats. The duration of the silent period was independent of the initial tension in the muscle and remained constant in spite of large variations in the twitch tension with springs of varying compliances inserted in series with the muscle. The responses of 42 tendon organs of the soleus to twitch contractions, passive stretch and fused tetanic contractions have been determined in Nembutal anaesthetized cats. The majority of the tendon organs had appreciably lower thresholds to active contraction than to passive stretch of the muscle. They were all excited by isometric twitches developing less than 160 g tension. There was an approximately linear relationship between the discharge frequency of the tendon organs and the tension in the muscle during isometric, graded, fused tetanic contractions of the muscle. The slope of this relationship varied between 2 and 18 imp/sec/100 g. It is concluded that the duration of the silent period in the decerebrate cat is primarily determined by the pause in the discharge of the primary endings of the muscle spindle during the twitch.