Effects of chronic centrifugation on skeletal muscle fibers in young developing rats
Martin, W.D.
Aviation Space and Environmental Medicine 51(5): 473-484
1980
ISSN/ISBN: 0095-6562 PMID: 6446280 Document Number: 168066
After 3 groups of 30-day-old male and female rats were centrifuged for 2, 4, 8 and 16 wk, their soleus and plantaris muscles were analyzed for changes in proportions of muscle fiber types. The groups were earth control, maintained at earth gravity without rotation, rotation control, subjected to a gravitational force of 1.05 G and 28 rpm, and rotation experimental, subjected to a gravitational force of 2 G and 28 rpm. Muscle fibers were classified into 4 fiber types on the basis of actomyosin ATPase activity as slow oxidative, fast oxidative glycolytic and either fast glycolytic (plantaris) or intermediate (soleus). Hypergravity resulted in an increase in slow oxidative fibers in soleus and the deep region of plantaris. Chronic rotation of males resulted in a decreased proportion of slow oxidative fibers in soleus relative to the earth control, but not of females treated similarly. The relationship of body weight to the changes in proportion of slow oxidative fibers is discussed.