Effects of use and disuse on growing skeletal muscle

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:5561388

Darr, K C

In the first series of experiments, the time course and extent of satellite cell activation were studied in the soleus and extensor digitorum longus (EDL) muscles of untrained growing and mature rats after a single bout of prolonged eccentric treadmill running. Satellite cell mitotic activity was quantitated in autoradiographs of whole-fiber segments after injection of {sup 3}H-thymidine. Labelling in growing muscles progressively increased to peak at 72 h postexercise, whereas mature muscles exhibited an earlier peak at 24 (soleus) and 48 (EDL) h, followed by a more rapid decline to control levels by 120 h postexercise. In all exercised muscles the calculated satellite cell activation was far greater than required to repair the small number of necrotic fibers identified at the light-microscopic levels. In a second series of experiments, postnatal growth of 20d old rat EDL and soleus muscles was studied after 3, 10, 20 and 30d of hindlimp suspension. Radial growth of suspended soleus myofibers was attenuated 76% over the total suspension period. Longitudinal growth rate, however, was accelerated 40% over weight-bearing controls. In contrast radial and longitudinal growth of EDL myofibers were minimally affected under similar conditions. Both the number and proliferative activity of satellite cells were severely reduced in individual myofibers by day 3 of suspension.

• Research Organization: Wisconsin Univ., Madison, WI (USA)
• OSTI ID: 5561388
• Country of Publication: United States
• Language: English

Related Subjects

550801* -- Morphology-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMAL GROWTH
ANIMALS
AUTORADIOGRAPHY
AZINES
BIOLOGICAL EFFECTS
CELL PROLIFERATION
EXERCISE
GROWTH
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
MAMMALS
MUSCLES
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RATS
RIBOSIDES
RODENTS
THYMIDINE
TRITIUM COMPOUNDS
VERTEBRATES