Review of spaceflight and hindlimb suspension unloading induced sarcomere damage and repair. Basic Appl Myol 1995;5(2):139-45
Date
01/01/1995Pubmed ID
11539271Scopus ID
2-s2.0-0029420480 (requires institutional sign-in at Scopus site) 61 CitationsAbstract
Hindlimb suspension unloading (HSU) and spaceflight microgravity induce atrophy of the slow adductor longus muscle fibers which, following reloading, exhibit eccentric contraction (EC)-like lesions (abnormal widening of sarcomeres with A band disruption and excessively wavy, extracted Z lines). These lesions are similar morphologically to those produced in normal muscles after strenuous eccentric exercise. It appears that atrophic muscles exhibit increased susceptibility to eccentric damage because lesions are produced during nonstressful voluntary movements upon return to weightbearing. The EC-like lesions are absent in the unweighted conditions, but appear in HSU rats 15-60 minutes after reloading and in space-flown rates about 4 hrs after landing. By 12 hours, many EC-like lesioned sarcomeres are fully covered by longitudinal patches of Z line-like material which increases in density by 48 hours, producing the so-called "Z line streaming" morphology. In this case, Z line streaming is indicative of rapid repair of damaged sarcomeres rather than the onset of sarcomere breakdown. Immunoelectron microscopy is necessary to determine the composition of this dense material. By 9 days of reloading at 1 gravity, sarcomeres have regained normal structure, except for very rare persistence of faint Z patches. The morphological data indicate that Z patches serve at least two functions: 1) to permit contractile force to be transmitted across the damaged sarcomeres and 2) to provide a scaffold upon which sarcomeres are reconstructed in an active functional muscle.
Author List
Riley DA, Thompson JL, Krippendorf BB, Slocum GRAuthor
Beth B. Krippendorf PhD Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsHindlimb Suspension
Male
Microscopy, Electron
Muscle, Skeletal
Muscular Atrophy
Physical Conditioning, Animal
Rats
Sarcomeres
Space Flight
Weightlessness
Weightlessness Simulation
