Fiber content and myosin heavy chain composition of muscle spindles in aged human biceps brachii.
The present study investigated potential age-related changes in human muscle spindles with respect to the intrafusal fiber-type content and myosin heavy chain (MyHC) composition in biceps brachii muscle. The total number of intrafusal fibers per spindle decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. Nuclear chain fibers in old spindles were short and some showed novel expression of MyHC alpha-cardiac. The expression of MyHC alpha-cardiac in bag1 and bag2 fibers was greatly decreased in the A region. The expression of slow MyHC was increased in nuclear bag1 fibers and that of fetal MyHC decreased in bag2 fibers whereas the patterns of distribution of the remaining MyHC isoforms were generally not affected by aging. We conclude that aging appears to have an important impact on muscle spindle composition. These changes in muscle spindle phenotype may reflect an age-related deterioration in sensory and motor innervation and are likely to have an impact in motor control in the elderly.
Liu
Jing-Xia
JX
Department of Integrative Medical Biology, Section for Anatomy, Umeå University, Umeå, Sweden.
Eriksson
Per-Olof
PO
Thornell
Lars-Eric
LE
Pedrosa-Domellöf
Fatima
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000648:ultrastructure*; D009470:Muscle Spindles / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure*; D018995:Myosin Heavy Chains / Q000096:biosynthesis / Q000737:chemistry*; D020033:Protein Isoforms / Q000096:biosynthesis / Q000737:chemistry
D020033:Protein Isoforms; D018995:Myosin Heavy Chains