The fast-twitch flexor digitorum longus (FDL) muscle was partially denervated by a unilateral section of the L7 ventral root. After approximately 100 days the isometric, force-velocity and histochemical properties of single motor units from the partially denervated muscle were determined. The diameter of the nerve axons supplying the muscle were also examined. The extrapolated maximum speed of sarcomere shortening (Vmax) of the enlarged motor units was significantly less than that of the control whole muscle Vmax. It is concluded that the motoneurone is capable of expanding its territory and therefore its tension generating capability without any apparent change in axonal diameter. In addition, the intrinsic properties of the muscle fibres are altered.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Bagust J, Knott S, Lewis DM, Luck JC, Westerman RA (1973) Isometric contractions of motor units in a fast twitch muscle of the cat. J Physiol (Lond) 231: 87–104
Brooke MH, Kaiser KK (1969) Some comments on the histochemical characterization of muscle adenosine triphosphate. J Histochem Cytochem 17: 431–432
Brown MC, Ironton R (1978) Sprouting and regression of neuromuscular synapses in partially denervated mammalian muscles. J Physiol (Lond) 278: 325–348
Burke RE, Levine DN, Tsairis P, Zajac FE (1973) Physiological types and histochemical profiles in motor units of the cat gastrocnemius. J Physiol (Lond) 234: 723–748
Edström L, Kugelberg E (1968) Histochemical composition, distribution of fibres and fatiguability of single motor units. Anterior tibial muscle of the rat. J Neurol Neurosurg Psychiatry 31: 424–433
Hatcher DD, Luff AR, Westerman RA (1982) Force-velocity characteristics of fractions of cat soleus and fledigitorum longus muscles. Proc Aust Physiol Pharmacol Soc 13: 119P
Luff AR (1985) Dynamic properties of fiber bundles from the rat sternomastoid muscle. Exp Neurol (in press)
Luff AR, Proske U, Webb SN (1984) The transformation of cross-reinnervated slow-twitch muscle after deafferentation in the cat. Exp Brain Res 55: 152–157
McManus JFA, Mowry RW (1960) Staining methods: histological and histochemical. Harper and Row, New York
Novikoff AB, Woo-Yung S, Drucker J (1961) Mitochondrial localization of oxidative enzymes: staining results with two tetrazolium salts. J Biophys Biochem Cytol 9: 47–59
Sriratana D (1979) Anatomy and physiology of the cat's flexor digitorum longus and flexor hallucis longus muscles. PhD Thesis, Monash University
Thompson W, Jansen JKS (1977) The extent of sprouting of remaining motor units in partially denervated immature and adult rat soleus muscle. Neuroscience 2: 523–535
Westerman RA (1978) Mechanisms of plasticity in mammalian nerve-muscle interactions. In: Porter, R. (ed), Studies in neurophysiology. Cambridge University Press, Cambridge, pp 309–332
Westerman RA, Chan HS, Ziccone SP, Sriratana D, Dennett X, Tate KA (1979) Plasticity of motor reinnervation in the kitten. In: Meisami E, Brazier MAB (eds) Neural growth and differentiation. Raven Press, New York, pp 397–432
About this article
Cite this article
Hatcher, D.D., Luff, A.R., Westerman, R.A. et al. Contractile properties of cat motor units enlarged by motoneurone sprouting. Exp Brain Res 60, 590–593 (1985). https://doi.org/10.1007/BF00236946
- Motor units
- Partial denervation
- Motoneurone sprouting