TY - JOUR
T1 - Age-related changes in diaphragm muscle contractile properties and myosin heavy chain isoforms
AU - Gosselin, Luc E.
AU - Johnson, Bruce D.
AU - Sieck, Gary C.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1994/7
Y1 - 1994/7
N2 - The present study sought to examine the effects of aging on the isometric contractile and fatigue properties as well as the myosin heavy chain (MCH) isoform composition of the rat diaphragm muscle. Male Fischer 344 (F344) specific pathogen-free rats 6 and 24 mo old were used in the study. Peak twitch force was ~23% lower (p < 0.05) in the senescent diaphragm compared with the young. Time to peak twitch force and one-half relaxation time of twitch force did not differ between groups. There was a significant decrease (15 to 18%, p < 0.05) in the specific force (N/cm2) of the senescent diaphragm at all stimulation frequencies (10 to 100 Hz) examined. In addition, the fatigability of the diaphragm did not significantly differ between the two groups. No significant changes in the distribution of MHC 1 and 2A isoforms were observed with aging. However, the contribution of MHC 2X significantly decreased with senescence (young, 37.5%; senescent, 30.5%), whereas the contribution of MHC 2B in the senescent diaphragm was significantly higher (young, 6.5%; senescent, 15.0%; p < 0.05). We conclude that the age-related decline in diaphragm muscle specific force is caused by intrinsic factors other than changes in MHC composition.
AB - The present study sought to examine the effects of aging on the isometric contractile and fatigue properties as well as the myosin heavy chain (MCH) isoform composition of the rat diaphragm muscle. Male Fischer 344 (F344) specific pathogen-free rats 6 and 24 mo old were used in the study. Peak twitch force was ~23% lower (p < 0.05) in the senescent diaphragm compared with the young. Time to peak twitch force and one-half relaxation time of twitch force did not differ between groups. There was a significant decrease (15 to 18%, p < 0.05) in the specific force (N/cm2) of the senescent diaphragm at all stimulation frequencies (10 to 100 Hz) examined. In addition, the fatigability of the diaphragm did not significantly differ between the two groups. No significant changes in the distribution of MHC 1 and 2A isoforms were observed with aging. However, the contribution of MHC 2X significantly decreased with senescence (young, 37.5%; senescent, 30.5%), whereas the contribution of MHC 2B in the senescent diaphragm was significantly higher (young, 6.5%; senescent, 15.0%; p < 0.05). We conclude that the age-related decline in diaphragm muscle specific force is caused by intrinsic factors other than changes in MHC composition.
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U2 - 10.1164/ajrccm.150.1.8025746
DO - 10.1164/ajrccm.150.1.8025746
M3 - Article
C2 - 8025746
AN - SCOPUS:0028310370
SN - 1073-449X
VL - 150
SP - 174
EP - 178
JO - American journal of respiratory and critical care medicine
JF - American journal of respiratory and critical care medicine
IS - 1
ER -