title: Myosin and actin expression and oxidation in aging muscle.
abstract: While the age-related loss in muscle mass partially explains the decline in strength, other yet undefined mechanisms contribute. This study investigates whether changes in myosin-actin stoichiometry and oxidative modification could help explain the decrement in muscle strength with aging. Protein expression and oxidation were evaluated in myosin and actin isolated from the soleus and semimembranosus muscles from young adult, old, and very old Fischer 344 rats. In the soleus muscle, actin and myosin content did not change with aging. In the semimembranosus, actin content was stable, but myosin exhibited decreased content in muscles from very old rats, resulting in a decrease in the myosin-to-actin ratio. 3-Nitrotyrosine and 4-hydroxy-2-nonenal were used as markers of protein oxidative damage. Although myosin and actin are modified with 3-nitrotyrosine and 4-hydroxy-2-nonenal, the extent of chemical modification does not increase with age. The results suggest that the decline in force production with age is not due to the accumulation of these two specific markers of protein oxidation on the myofibrillar proteins. Additionally, age-dependent changes in myofibrillar stoichiometry do not contribute to the decline in force production in the soleus, but may play a role in the semimembranosus with advanced age.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Minnesota, Minneapolis, Minnesota 55455, USA. thomp067@umn.edu
authors.forename: Ladora V
authors.initials: LV
authors.lastname: Thompson
authors.forename: David
authors.initials: D
authors.lastname: Durand
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Fugere
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Ferrington
mesh_terms: D000199:Actins / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000818:Animals; D015870:Gene Expression / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D000199:Actins; D009218:Myosins