[Electrophysiological characteristics of the isolated muscle spindle in rats].

The aim of this study was to observe the electrophysiological characteristics of the isolated rat muscle spindle. The muscle spindle was isolated from rat soleus and the afferent discharge of the isolated muscle spindle was recorded by air-gap technique. In the basic physiological salt solution, the spontaneous impulses of muscle spindle were at a lower level with irregular intervals. The mean frequency of afferents was (51.78 ± 25.63) impulses/1 000 s (n = 13). The muscle spindle afferents were significantly increased and maintained over time by the addition of certain amino acids during the observation. The number of the action potential recorded per 1 000 s was 200-1 000 [mean: (687.62 ± 312.56) impulses/1 000 s, n = 17]. In addition to the typical propagated action potential, a large number of abortive spikes were observed. The results indicate that the activities of isolated muscle spindles in rats can be well maintained by the addition of certain amino acids. The results initially establish and provide the possibility for further research conducted in isolated rat muscle spindles.