Ontogenetic, gravity-dependent development of rat soleus muscle
| Autor: | David L. Allen, Yoshinobu Ohira, Takato Tanaka, Takeshi Nomura, V. Reggie Edgerton, Ikuya Nonaka, Fuminori Kawano, Tomoo Yoshinaga, Roland R. Roy |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Electrophoresis
Male medicine.medical_specialty Physiology Ontogeny Muscle Fibers Skeletal Hindlimb Biology Muscle Development medicine.disease_cause Weight-bearing Weight-Bearing Internal medicine Myosin medicine Animals Weaning Rats Wistar Muscle Skeletal Postnatal day Cell Nucleus Soleus muscle Microscopy Confocal Myosin Heavy Chains Age Factors Skeletal muscle Organ Size Cell Biology Immunohistochemistry Rats Phenotype Endocrinology medicine.anatomical_structure Animals Newborn Female Gravitation |
| Zdroj: | American Journal of Physiology-Cell Physiology. 280:C1008-C1016 |
| ISSN: | 1522-1563 0363-6143 |
| DOI: | 10.1152/ajpcell.2001.280.4.c1008 |
| Popis: | We tested the hypothesis that rat soleus muscle fiber growth and changes in myosin phenotype during the postnatal, preweaning period would be largely independent of weight bearing. The hindlimbs of one group of pups were unloaded intermittently from postnatal day 4 to day 21: the pups were isolated from the dam for 5 h during unloading and returned for nursing for 1 h. Control pups were either maintained with the dam as normal or put on an alternating feeding schedule as described above. The enlargement of mass (approximately 3 times), increase in myonuclear number (approximately 1.6 times) and myonuclear domain (approximately 2.6 times), and transformation toward a slow fiber phenotype (from 56 to 70% fibers expressing type I myosin heavy chain) observed in controls were inhibited by hindlimb unloading. These properties were normalized to control levels or higher within 1 mo of reambulation beginning immediately after the unloading period. Therefore, chronic unloading essentially stopped the ontogenetic developmental processes of 1) net increase in DNA available for transcription, 2) increase in amount of cytoplasm sustained by that DNA pool, and 3) normal transition of myosin isoforms that occur in some fibers from birth to weaning. It is concluded that normal ontogenetic development of a postural muscle is highly dependent on the gravitational environment even during the early postnatal period, when full weight-bearing activity is not routine. |
| Databáze: | OpenAIRE |
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