Patterns of soleus muscle potentials to repetitive stimulation in young and aged rats

Muscle potentials were recorded in the soleus muscle of Wistar rats anesthetized with urethane or Nembutal. The time course of their changes induced by repetitive stimulation of sciatic nerves at 5 Hz for 10 min was compared for young and aged rats. When stimulation commenced, muscle potentials from young rats were somewhat facilitated, followed by slight depression below control values, and thereafter they were gradually potentiated. On the contrary, muscle potentials from aged rats were rapidly reduced, attaining plateau levels 2 min or so after the onset of repetitive stimulation at 5 Hz.