[Responses of the muscle spindles of tenotomized and hypertrophied muscles to stretch and vibration].

Responses of primary and secondary endings of muscle spindles were studied after tenotomy and hypertrophy in the cat soleus muscles. Under constant load (100 g) background activity of primary endings in a control muscle was 17 +/- 1.5 imp/s. It did not change in hypertrophic muscle and increased after tenotomy to 26 +/- 1.5 imp/s. Responses of secondary endings did not change under the same conditions. The frequency of a response from primary and secondary endings of tenotomized and hypertrophic muscles were higher during dynamic and static phase of stretching as compared to response of normal muscle spindles. Primary endings of tenotomized and hypertrophic muscles were able to repeat vibration up to 200 Hz, while secondary endings responded only with some increase in the discharge frequency.