Satellite cell proliferation exercise-induced increases and new myonuclear accretion in rat skeletal muscle.
Smith, Heather K., Linda Maxwell, Carol D. Rodgers, Nancy H. McKee, and Michael J. Plyley.
Departments of 1Sport and Exercise Science and 2Pathology, University of Auckland, Auckland, New Zealand; and 3Faculty of Physical Education and Health and 4Department of Surgery, University of Toronto, Toronto, Ontario, Canada M5S 1A1
APStracts 8:0020A, 2001.
The effects of increased functional loading on early cellular regenerative events after exercise-induced injury in adult skeletal muscle were examined with the use of in vivo labeling of replicating myofiber nuclei and immunocyto- and histochemical techniques. Satellite cell proliferation in the soleus (Sol) of nonexercised rats (0.4 ± 0.2% of fibers) was unchanged after an initial bout of declined treadmill exercise but was elevated after two (1.0 ± 0.2%, P = 0.01), but not four or seven, daily bouts of the same task. Myonuclei produced over the 7-day period comprised 0.9-1.9% of myonuclei in isolated fibers of Sol, tibialis anterior, and vastus intermedius of nonexercised rats. The accretion of new myonuclei was enhanced (P = 0.05) in Sol and vastus intermedius by the initial exercise followed by normal activity (to 3.1-3.4% of myonuclei) and more so by continued daily exercise (4.2-5.3%). Observed coincident with a lower incidence of histological fiber injury and unchanged fiber diameter and myonuclei per millimeter, the greater new myonuclear accretion induced by continued muscle loading may contribute to an enhanced fiber repair and regeneration after exercise-induced injury.
Received 13 September 2000; accepted in final form 6 November 2000
APS Manuscript Number A305-0.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 January 2001