title: Post-tetanic effects in motor units of fast and slow twitch muscle of the cat.
abstract: 1. Motor unit twitches were examined in cat flexor digitorum longus (fast twitch) and soleus (slow twitch) muscles. The time course of the effects of a standard tetanus on the peak twitch tension was plotted and the maximal potentiation or depression (the post-tetanic ratio) was measured.2. The post-tetanic ratio decreased continuously as the twitch time to peak of motor units increased; motor units from flexor digitorum longus and soleus could be described as a single population. The closest approximation to a linear relationship was found by plotting post-tetanic ratio against the reciprocal of time to peak.3. The post-tetanic ratio was also related to the ratio of tetanic to twitch tension. The time of maximum potentiation or depression occurred between 1 and 11 sec, but this variable was unrelated to the time to peak or any other characteristic of the motor unit.
mesh_terms: D000818:Animals; D002415:Cats; D004558:Electric Stimulation; D004576:Electromyography; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction; D009132:Muscles / Q000294:innervation / Q000502:physiology*; D009431:Neural Conduction