Compensatory adaptations of skeletal muscle composition to a long-term functional overload.
Compensatory hypertrophy of rat plantaris muscle was induced by ablating the synergistic gastrocnemius muscle. The sham-operated contralateral muscle served as a control. Within 5, 30 and 60 days postoperatively, the wet weight of the hypertrophied plantaris was 40, 64, and 109% greater, respectively, than the contralateral control. Two patterns of changing muscle composition emerged with compensatory hypertrophy: (1) an early (less than or equal to 5 days) increase in DNA content (+190%) which resulted in a sharp decline in the wet weight per nucleus ratio (-50%). This coincided with an increase in sarcoplasmic and stromal proteins and a fall in myofibrillar protein concentration. These changes were followed by (2) a secondary increase (30-60 days postoperatively) in the proportions of myofibrillar proteins with a corresponding decline in sarcoplasmic proteins.
D000222:Adaptation, Physiological; D000818:Animals; D002467:Cell Nucleus / Q000032:analysis; D004247:DNA / Q000032:analysis; D006984:Hypertrophy / Q000503:physiopathology; D009124:Muscle Proteins / Q000032:analysis; D009132:Muscles / Q000032:analysis / Q000033:anatomy & histology / Q000502:physiology*; D009210:Myofibrils / Q000032:analysis; D009929:Organ Size; D051381:Rats; D012519:Sarcoplasmic Reticulum / Q000032:analysis; D014867:Water / Q000032:analysis
D009124:Muscle Proteins; D014867:Water; D004247:DNA