Age effect on expression of myosin heavy and light chain isoforms in suspended rat soleus muscle

• Published in: Journal of applied physiology (1985) Vol. 86; no. 5; pp. 1483 - 1489
• Main Authors: Saitoh, Ayako, Okumoto, Tadashi, Nakano, Hiroshi, Wada, Masanobu, Katsuta, Shigeru
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Physiological Soc 01.05.1999; American Physiological Society
• Subjects: Age; Aging - physiology; Anatomy & physiology; Animals; Biological and medical sciences; Body Weight - physiology; Electrophoresis, Polyacrylamide Gel; Female; Fundamental and applied biological sciences. Psychology; Hindlimb Suspension - physiology; Influence; Isomerism; Muscle Development; Muscle, Skeletal - chemistry; Muscle, Skeletal - growth & development; Muscle, Skeletal - metabolism; Muscular system; Myosin Heavy Chains - biosynthesis; Myosin Heavy Chains - chemistry; Myosin Light Chains - biosynthesis; Myosin Light Chains - chemistry; Organ Size - physiology; Rats; Rats, Wistar; Rodents; Space life sciences; Striated muscle. Tendons; Studies; Vertebrates: osteoarticular system, musculoskeletal system; Molecular form; Rat; Rodentia; Contractile protein; Lower limb; Suspension; Weightlessness; Striated muscle; Gene expression; Soleus muscle; Vertebrata; Mammalia; Simulation; Myosin; Plasticity; Age
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.1999.86.5.1483

1  Department of Physical Therapy, School of Physical and Occupational Therapy, Hakone National Hospital, Kanagawa 250-0032; 2  Research Center for Aging and Adaptation, School of Medicine, Shinsyu University, Nagano 390-8621; 3  Department of Child Education, Nakamura Gakuen University, Fukuoka 814-0104; 4  Faculty of Integrated Arts and Sciences, Hiroshima University, Hiroshima 739-8521; and 5  Institute of Health and Sport Sciences, University of Tsukuba, Ibaraki 305-0036, Japan This study was designed to test the hypothesis that myosin heavy (MHC) and light chain (MLC) plasticity resulting from hindlimb suspension (HS) is an age-dependent process. By using an electrophoretic technique, the distribution of MHC and MLC isoforms was quantitatively evaluated in the soleus muscles from 3- or 12-wk-old rats after 1-3 wk of HS treatment was maintained. In normal 12- and 15-wk-old rats, the soleus muscles contained a predominance of MHC I (~94%) with small amounts of MHC IIa , but not MHC IId or MHC IIb . The suspended muscles of adult rats were characterized by the appearance of MHC IIb and MHC IId , the latter reaching ~6% after 3 wk of HS treatment. In contrast to changes in MHC, HS did not induce a transition in the MLC pattern in the soleus muscles from adult rats. Compared with adult rats, in juveniles HS had a much more pronounced effect on the shift toward faster MHC and MLC isoform expression. The soleus muscles of 6-wk-old rats after 3 wk of HS were composed of 37.0% MHC I , 19.1% MHC IIa , 23.7% MHC IId , and 20.2% MHC IIb . Changes in MLC isoforms consisted of an increase in MLC 1f and MLC 2f concomitant with a decrease in MLC 2s . These results indicate the existence of a differential effect of HS on MHC and MLC transitions that appears to be age dependent. They also suggest that the suspended soleus muscles from young rats may acquire the intrinsic contractile properties that are intermediate between those in the normal soleus and typical fast-twitch skeletal muscles. development; hindlimb suspension; transition