title: Effect of increased physical activity on growth and differentiation of regenerating rat soleus muscle.
abstract: Our purpose was to determine the effect of physical exercise on growth and differentiation during regeneration of a slow-twitch muscle. Degeneration/regeneration of the left soleus muscles of Wistar female rats was induced by injection of a snake venom. Muscular differentiation was studied by monitoring the sequential expression of the various myosin heavy chain isoforms (MHCs). Rats were assigned to one of two groups: cage sedentary (n = 14) or exercised (n = 16). The exercise programme began 1-day post-injection and the rats ran 1 h/day on a motorized treadmill. Then, 9 and 25 days after venom treatment, the soleus MHC phenotype as determined by immunohistology, electrophoresis and immunoblotting, was studied. At 25 days the expression of MHCs by regenerating soleus was not changed by the increased level of physical activity (P > 0.05). Exercised and sedentary regenerating muscles contained similar numbers of type-I fibres (100% of total fibres), levels of MHC-1 (85.4 and 89.5% of total MHCs), MHC-2a and M/HC-2x/d and their fibres expressed MHC-1 (100% of total fibres) and MHC-2 (45-50%) in the same way. Moreover, the masses of regenerating and nonregenerating soleus were significantly increased by physical exercise (P < 0.02). At 9 days no effect of muscular exercise was found. In conclusion, endurance exercise did not alter differentiation of regenerating soleus. Moreover regenerating soleus can respond to increased physical activity by enhancing its mass in the same way as mature muscle.
authors.affiliation: Laboratoire de Physiologie des Adaptations, Faculté de Médecine Cochin-Port-Royal, Université René Descartes, Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Ferry
authors.forename: P
authors.initials: P
authors.lastname: Noirez
authors.forename: I B
authors.initials: IB
authors.lastname: Salah
authors.forename: C
authors.initials: C
authors.lastname: Le Page
authors.forename: J P
authors.initials: JP
authors.lastname: Wahrmann
authors.forename: M
authors.initials: M
authors.lastname: Rieu
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D015151:Immunoblotting; D007150:Immunohistochemistry; D007273:Injections, Intramuscular; D007700:Kinetics; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D012910:Snake Venoms / Q000008:administration & dosage
chemical_list: D012910:Snake Venoms; D018995:Myosin Heavy Chains