Influence of the delay of denervation on slow striated muscle resistance to slow-to-fast conversion following cross-innervation.

Abstract

Cross-reinnervation, in cases of nerve repair or nerve transfer, can be the consequence of wrong connections which are surgically induced between the different types of motoneurons (fast and slow). A slow muscle nerve is able to convert a fast muscle virtually completely to the slow fibre type, whereas a fast muscle nerve exerts an incomplete control over the properties of a slow muscle. Our experiments show that following delayed cross-reinnervation, a statistically significant slow-to-fast transformation of the soleus muscle was observed, with a maximum when nerve repair was performed 6 weeks following nerve section in the rat model. Thus, the negative consequences on nerve and muscle relationship due to cross-reinnervation in the case of wrong connections between slow and fast motoneurons after conventional nerve suture or in the case of nerve transfer could be minimised by imposing a delay before nerve repair.