title: Myofibril and sarcoplasmic reticulum changes with exercise and growth.
abstract: The intent of this study was to observe the effects of different treadmill running programs upon selected biochemical properties of soleus muscle from young rats. Young 10 day litter-mates were assigned to endurance (E), spring (S) and control (C) groups. Each was partitioned into either 21 or 51 day exercising groups and 10 day controls. For C the myofibril ATPase activity at 21 and 51 days were lower than 10 day activity (p less than or equal to 0.05). In the 51 day E group ATPase activity (0.378 +/- 0.009 mumol Pi X mg-1 X min-1) was greater than at 10 and 21 days (0.307 +/- 0.006 and 0.323 +/- 0.008 mumol Pi X mg-1 X min-1) (p less than or equal to 0.05). No change occurred in the S group from 10 to 21 and 51 days (p greater than or equal to 0.05). Both the 21 and 51 day S (0.318 +/- 0.011 and 0.399 +/- 0.010 mumol Pi X mg-1 X min-1) and E (0.323 +/- 0.008 and 0.378 +/- 0.009 mumol Pi X mg-1 X min-1) groups had higher activity compared to the C group (0.193 +/- 0.029 and 0.172 +/- 0.031 mumol Pi X mg-1 X min-1) (p less than or equal to 0.05). Maturation (10--51 day) resulted in a lowered sarcoplasmic reticulum (SR) yield and Ca2+ binding (p less than or equal to 0.05) while Ca2+ uptake ability did not change (p greater than or equal to 0.05). SR yield, Ca2+ binding and uptake were not altered with S training (p greater than or equal to 0.05). The E training resulted in greater Ca2+ uptake at 51 days compared to C and S (p less than or equal to 0.05), with no change in Ca2+ binding (p greater than or equal to 0.05). The data suggest that E training alters the normal development pattern of young rat soleus muscle.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism; D006128:Growth; D008565:Membrane Proteins / Q000032:analysis; D009132:Muscles / Q000378:metabolism / Q000502:physiology; D009210:Myofibrils / Q000201:enzymology / Q000502:physiology*; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D005082:Physical Exertion; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000032:analysis / Q000502:physiology*
chemical_list: D008565:Membrane Proteins; D006003:Glycogen; D000251:Adenosine Triphosphatases; D002118:Calcium