Submitted on July 19, 2004
Accepted on March 17, 2005
Dual effect of deafferentation on contractile characteristics and sarcoplasmic reticulum properties in rat soleus fibers
Y. Mounier1*, V. Montel1, F. Picquet1, L. Stevens1, B. Bastide1, and M. Falempin1
1 Universite des Sciences et Technologies de Lille, Laboratoire de Plasticite Neuromusculaire, Villeneuve d'Ascq, France
* To whom correspondence should be addressed. E-mail: Yvonne.Mounier{at}univ-lille1.fr.
The neural message is known to play a key role in muscle development and function. We analyzed the specific role of the afferent message on the functional regulation of two subcellular muscle components involved in the contractile mechanism: the contractile proteins and the sarcoplasmic reticulum (SR). Rats were submitted to bilateral deafferentation (DEAF group) by section of the dorsal roots L3 to L5 after laminectomy. Experiments were carried out in single skinned fibers of the soleus muscle. The maximal force developed by the contractile proteins was increased in DEAF group when compared to control, despite a decrease in muscle mass by 17 %. The tension-pCa relationship was shifted toward lower calcium (Ca2+) concentrations. Different functional properties of the SR of DEAF soleus were examined by using caffeine-induced contractions. The caffeine sensitivity of the Ca2+ release was decreased after deafferentation and RyR1 isoform was expressed at a lower level. The rate of Ca2+ uptake was only slightly increased. The results underlined the dual effect of the afferent input on the functional regulation of both contractile proteins and sarcoplasmic reticulum.
