Contractile and histochemical properties of denervated and reinnervated fast and slow skeletal muscles of new-born and adult guinea-pigs
Guttmann, E.; Melichna, J.A.
Physiologia Bohemoslovaca 28(1): 35-42
1979
ISSN/ISBN: 0369-9463 PMID: 155829 Document Number: 145659
Denervation prolongs all parameters of contractile behavior in both fast and slow muscles of young and adult guinea pigs. Prolongation of contraction time is more pronounced in the fast extensor digitorum longus (EDL) muscle in both young and adult animals. Denervation in adult animals does not result in the reappearance of muscle fibers with high ATPase activity (Type II) in the slow soleus (SOL) muscle as in denervated muscles of young animals. Reinnervation after crushing of the nerve results in recovery of normal contraction time after a transient prolongation in fast and slow muscles of young and adult animals. A mixed muscle fiber pattern with respect to ATPase activity, as seen at birth, is established in the fast, a homogeneous one in the slow muscle of both young and adult guinea pigs. A heterogeneous fiber pattern is seen only temporarily during reinnervation of the SOL muscle of young animals. The motor unit and the muscle fiber pattern are established at birth in the case of the fast EDL muscle and in the adult animals in the case of slow SOL muscle. Once established, the fiber pattern is maintained or recovered after denervation and reinnervation of fast and slow muscles, in young and adult animals, respectively. A close relation of contractile and histochemical properties was found in normal, denervated and reinnervated muscles.