Response of Old Skeletal Muscle to 8 Weeks of Electrical Stimula - tion ( Should We Change the Conventional Electrical Stimulation Protocol for Cardiomyoplasty ? )

We hypothesized that the conditioned muscles of elderly organisms have different responses to electrical stimulation than that of young adult organisms. One-year-old sheep and eight-year-old elderly sheep were used for this investigation. Results. The latissimus dorsi muscle (LDM) of old sheep has less fatigue resistance than LDM of younger animals. In all animals, LDH-5 fractions decreased after eight weeks ES; LDH-1+2 fractions increased. After a two week delay, the data completely returned to baseline values in old adult animals. The percent area occupied by mitochondria in old sheep was less after ES than in younger animals. In all animals, the mitochondrial area increased after ES and reverted to baseline values after the delay. The number of nuclei and fibers considerably increased after ES. Conclusions. Young skeletal muscle obtains more plasticity than adult muscle during ES. Elderly skeletal muscle does not convert to a fatigue resistant state as completely as adult skeletal muscle during a conventional eight week ES protocol. It is necessary to change and prolong the ES protocol for elderly patients.