Alterations of intrinsic tongue muscle properties with aging.
BACKGROUND
Age-related decline in the intrinsic lingual musculature could contribute to swallowing disorders, yet the effects of age on these muscles is unknown. We hypothesized there is reduced muscle fiber size and shifts to slower myosin heavy chain (MyHC) fiber types with age.


METHODS
Intrinsic lingual muscles were sampled from 8 young adult (9 months) and 8 old (32 months) Fischer 344/Brown Norway rats. Fiber size and MyHC were determined by fluorescent immunohistochemistry.


RESULTS
Age was associated with a reduced number of rapidly contracting muscle fibers, and more slowly contracting fibers. Decreased fiber size was found only in the transverse and verticalis muscles.


CONCLUSIONS
Shifts in muscle composition from faster to slower MyHC fiber types may contribute to age-related changes in swallowing duration. Decreasing muscle fiber size in the protrusive transverse and verticalis muscles may contribute to reductions in maximum isometric tongue pressure found with age. Differences among regions and muscles may be associated with different functional demands. Muscle Nerve 56: E119-E125, 2017.
Department of Surgery, University of Wisconsin-Madison, 1300 University Avenue, Madison, Wisconsin, 53706, USA.
Miranda J
MJ
Cullins
Department of Surgery, University of Wisconsin-Madison, 1300 University Avenue, Madison, Wisconsin, 53706, USA.
Nadine P
NP
Connor
D000375:Aging / Q000473:pathology* / Q000502:physiology*; D000818:Animals; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000473:pathology / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344; D014059:Tongue / Q000473:pathology* / Q000502:physiology*
age; dysphagia; lingual; swallow; tongue