scholarly journals Overexpression of HSP10 in skeletal muscle of transgenic mice prevents the age-related fall in maximum tetanic force generation and muscle cross-sectional area

2010 ◽  
Vol 299 (1) ◽  
pp. R268-R276 ◽  
Author(s):  
Anna C. Kayani ◽  
Graeme L. Close ◽  
Wolfgang H. Dillmann ◽  
Ruben Mestril ◽  
Malcolm J. Jackson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Cross Sectional Area ◽  
Force Generation ◽  
Sectional Area ◽  
Wild Type ◽  
Cross Sectional ◽  
Tetanic Force ◽  
Age Related ◽  
Muscle Cross Sectional Area

Skeletal muscle atrophy and weakness are major contributors to frailty and impact significantly on quality of life of older people. Muscle aging is characterized by a loss of maximum tetanic force (Po) generation, primarily due to muscle atrophy, to which mitochondrial dysfunction is hypothesized to contribute. We hypothesized that lifelong overexpression of the mitochondrial heat shock protein (HSP) HSP10 in muscle of mice would protect against development of these deficits. Po generation by extensor digitorum longus muscles of adult and old wild-type and HSP10-overexpressing mice was determined in situ. Muscles were subjected to damaging lengthening contractions, and force generation was remeasured at 3 h or 28 days to examine susceptibility to, and recovery from, damage, respectively. Muscles of old wild-type mice had a 23% deficit in Po generation and a 10% deficit in muscle cross-sectional area compared with muscles of adult wild-type mice. Overexpression of HSP10 prevented this age-related fall in Po generation and reduction in cross-sectional area observed in muscles of old wild-type mice. Additionally, overexpression of HSP10 protected against contraction-induced damage independent of age but did not improve recovery if damage occurred. Preservation of muscle force generation and CSA by HSP10 overexpression was associated with protection against the age-related accumulation of protein carbonyls. Data demonstrate that development of age-related muscle weakness may not be inevitable and show, for the first time, that lifelong overexpression of an HSP prevents the age-related loss of Po generation. These findings support the hypothesis that mitochondrial dysfunction is involved in the development of age-related muscle deficits.

scholarly journals Genetic and environmental influences on skeletal muscle phenotypes as a function of age and sex in large, multigenerational families of African heritage

2007 ◽  
Vol 103 (4) ◽  
pp. 1121-1127 ◽  
Author(s):  
Steven J. Prior ◽  
Stephen M. Roth ◽  
Xiaojing Wang ◽  
Candace Kammerer ◽  
Iva Miljkovic-Gacic ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Lean Mass ◽  
Genetic Correlations ◽  
Cross Sectional Area ◽  
Calf Muscle ◽  
Sectional Area ◽  
Cross Sectional ◽  
African Heritage ◽  
Genetic Components ◽  
Muscle Cross Sectional Area

The aim of this study was to estimate the heritability of and environmental contributions to skeletal muscle phenotypes (appendicular lean mass and calf muscle cross-sectional area) in subjects of African descent and to determine whether heritability estimates are impacted by sex or age. Body composition was measured by dual-energy X-ray absorptiometry and computed tomography in 444 men and women aged 18 yr and older (mean: 43 yr) from eight large, multigenerational Afro-Caribbean families (family size range: 21–112). Using quantitative genetic methods, we estimated heritability and the association of anthropometric, lifestyle, and medical variables with skeletal muscle phenotypes. In the overall group, we estimated the heritability of lean mass and calf muscle cross-sectional area (h2 = 0.18–0.23, P < 0.01) and contribution of environmental factors to these phenotypes ( r2 = 0.27–0.55, P < 0.05). In our age-specific analysis, the heritability of leg lean mass was lower in older vs. younger individuals (h2 = 0.05 vs. 0.23, respectively, P = 0.1). Sex was a significant covariate in our models ( P < 0.001), although sex-specific differences in heritability varied depending on the lean mass phenotype analyzed. High genetic correlations (ρG = 0.69–0.81; P < 0.01) between different lean mass measures suggest these traits share a large proportion of genetic components. Our results demonstrate the heritability of skeletal muscle traits in individuals of African heritage and that heritability may differ as a function of sex and age. As the loss of skeletal muscle mass is related to metabolic abnormalities, disability, and mortality in older individuals, further research is warranted to identify specific genetic loci that contribute to these traits in general and in a sex- and age-specific manner.

Microcirculatory structure-function relationships in skeletal muscle of diabetic rats

1994 ◽  
Vol 266 (4) ◽  
pp. H1502-H1511 ◽  
Author(s):  
W. L. Sexton ◽  
D. C. Poole ◽  
O. Mathieu-Costello
Keyword(s):  
Skeletal Muscle ◽  
Structure Function ◽  
Surface Area ◽  
Muscle Atrophy ◽  
Muscle Fiber ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Diffusing Capacity ◽  
Capillary Surface ◽  
Cross Sectional

The effects of streptozotocin-induced diabetes on microcirculatory structure-function relationships in skeletal muscle were studied in control (C) and diabetic (D; 65 mg/kg streptozotocin ip) rats 6-8 wk after injection. Capillary exchange capacity was determined from measurements of capillary filtration coefficient (CFC) and permeability-surface area product (PS) for 51Cr-labeled EDTA in maximally vasodilated (papaverine), isolated hindquarters of C (n = 9) and D (n = 12) rats. Capillary numerical density, length, surface area, capillary geometry, and muscle fiber cross-sectional area were determined using morphometric methods in perfusion-fixed plantaris muscles from a second series of C (n = 5) and D (n = 6) rats. Hindquarters of D rats (61 +/- 3 g) weighed less than C rats (90 +/- 3 g) because of marked muscle atrophy. Minimal total vascular resistance was lower in D rats (P < or = 0.05), indicating an increased flow capacity. CFC was not different in C and D rats (0.0282 +/- 0.0020 vs. 0.0330 +/- 0.0025 ml.min-1.mmHg-1 x 100 g-1, respectively). The relationship between PS and flow was depressed in D rats (P < or = 0.05) compared with C rats, which indicated a reduced capillary diffusing capacity. Plantaris muscle weight was 41% less in D rats (174 +/- 9 vs. 293 +/- 11 mg; P < or = 0.001). Morphometric analysis revealed that muscle fiber cross-sectional area was reduced 39% in D rats, which, despite a lower capillary-to-fiber ratio (1.59 +/- 0.04 vs. 2.12 +/- 0.13; P < or = 0.001), resulted in a 27% increase in capillary density in D rats. Capillary diameter was less in D rats (3.58 +/- 0.12 vs. 4.51 +/- 0.23 microns; P < or = 0.005). Total capillary surface area was reduced 42% in D rats; however, capillary surface area per muscle fiber volume was unchanged in D rats (231 +/- 34 vs. 237 +/- 16 cm-1). These data indicate that there is remodeling of the capillary bed in skeletal muscle of D rats, resulting in a reduction in total microvascular surface area. The reduction in capillary surface area is proportional to the degree of muscle atrophy in D rats such that functional microvascular surface area per tissue mass (e.g., CFC) is unchanged. The lower diffusing capacity (PS) in D rats suggests that either small solute permeability is reduced and/or there is greater perfusion heterogeneity in D rat skeletal muscle.

The Effects of Non-Weight Bearing on Skeletal Muscle in Older Rats: an Interrupted Bout versus an Uninterrupted Bout

2004 ◽  
Vol 5 (3) ◽  
pp. 195-202 ◽  
Author(s):  
Alissa Guildner Gehrke ◽  
Margaret Sheie Krull ◽  
Robin Shotwell McDonald ◽  
Tracy Sparby ◽  
Jessica Thoele ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Weight Bearing ◽  
Cross Sectional Area ◽  
Type I ◽  
Type Ii ◽  
Sectional Area ◽  
Cross Sectional ◽  
Age Related ◽  
Type Ii Fibers

Age-related changes in skeletal muscle, in combination with bed rest, may result in a poorer rehabilitation potential for an elderly patient. The purpose of this study was to determine the effects of non-weight bearing (hind limb unweighting [HU]) on the soleus and extensor digitorum longus (EDL) in older rats. Two non-weight bearing conditions were used: an uninterrupted bout of HU and an interrupted bout of HU. Twenty-one rats were randomly placed into 1 of 3 groups: control, interrupted HU (2 phases of 7 days of HU, separated by a 4-day weight-bearing phase) and an uninterrupted HU (18 uninterrupted days of HU). Following non-weight bearing, the soleus and EDL muscles were removed. Fiber type identification was performed by myofibrillar ATPase and cross-sectional area was determined. The findings suggest that any period of non-weight bearing leads to a decrease in muscle wet weight (19%-45%). Both type I and type II fibers of the soleus showed atrophy (decrease in cross-sectional area, 35%-44%) with an uninterrupted bout of non-weight bearing. Only the type II fibers of the soleus showed recovery with an interrupted bout of weight bearing. In the EDL, type II fibers were more affected by an uninterrupted bout of non-weight bearing (15% decrease in fiber size) compared to the type I fibers. EDL type II fibers showed more atrophy with interrupted bouts of non-weight bearing than with a single bout (a 40% compared to a 15% decrease). This study shows that initial weight bearing after an episode of non-weight bearing may be damaging to type II fibers of the EDL.

Anthropometric Prediction of Skeletal Muscle Cross-sectional Area in Persons with Spinal Cord Injury

2016 ◽  
Vol 48 ◽  
pp. 894
Author(s):  
Rodney C. Wade ◽  
Ashraf S. Gorgey ◽  
Jennifer Hubert ◽  
Ryan Sumrell ◽  
Justin Bengel ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cord Injury ◽  
Muscle Cross Sectional Area

scholarly journals A transient antioxidant stress response accompanies the onset of disuse atrophy in human skeletal muscle

2009 ◽  
Vol 107 (2) ◽  
pp. 549-557 ◽  
Author(s):  
Luciano Dalla Libera ◽  
Barbara Ravara ◽  
Valerio Gobbo ◽  
Elena Tarricone ◽  
Maurizio Vitadello ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Skeletal Muscle ◽  
Stress Response ◽  
Muscle Atrophy ◽  
Cross Sectional Area ◽  
Heme Oxygenase 1 ◽  
Sectional Area ◽  
Cross Sectional ◽  
Protein Levels ◽  
Antioxidant Stress

It is presently unknown whether oxidative stress increases in disused skeletal muscle in humans. Markers of oxidative stress were investigated in biopsies from the vastus lateralis muscle, collected from healthy subjects before [ time 0 (T0)], after 1 wk (T8), and after 5 wk (T35) of bed rest. An 18% decrease in fiber cross-sectional area was detected in T35 biopsies ( P < 0.05). Carbonylation of muscle proteins significantly increased about twofold at T35 ( P < 0.02) and correlated positively with the decrease in fiber cross-sectional area ( P = 0.04). Conversely, T8 biopsies showed a significant increase in protein levels of heme oxygenase-1 and glucose-regulated protein-75 (Grp75)/mitochondrial heat shock protein-70, two stress proteins involved in the antioxidant defense ( P < 0.05). Heme oxygenase-1 increase, which involved a larger proportion of slow fibers compared with T0, appeared blunted in T35 biopsies. Grp75 protein level increased threefold in T8 biopsies and localized especially in slow fibers ( P < 0.025), to decrease significantly in T35 biopsies ( P < 0.05). Percent change in Grp75 levels positively correlated with fiber cross-sectional area ( P = 0.01). Parallel investigations on rat soleus muscles, performed after 1–15 days of hindlimb suspension, showed that Grp75 protein levels significantly increased after 24 h of unloading ( P = 0.02), i.e., before statistically significant evidence of muscle atrophy, to decrease thereafter in relation to the degree of muscle atrophy ( P = 0.03). Therefore, in humans as in rodents, disuse muscle atrophy is characterized by increased protein carbonylation and by the blunting of the antioxidant stress response evoked by disuse.

scholarly journals A Comparison of Techniques for Estimating and Detecting Changes in Skeletal Muscle Cross-Sectional Area

2019 ◽  
Vol 51 (Supplement) ◽  
pp. 945
Author(s):  
Johnathon H. Moore ◽  
Cody T. Haun ◽  
Emily L. Grandprey ◽  
Katelyn P. Joubert ◽  
Christopher G. Vann ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Comparison Of Techniques ◽  
Muscle Cross Sectional Area

Effect of acute head-down tilt on skeletal muscle cross-sectional area and proton transverse relaxation time

1996 ◽  
Vol 81 (4) ◽  
pp. 1572-1577 ◽  
Author(s):  
Michael S. Conley ◽  
Jeanne M. Foley ◽  
Lori L. Ploutz-Snyder ◽  
Ronald A. Meyer ◽  
Gary A. Dudley
Keyword(s):  
Skeletal Muscle ◽  
Relaxation Time ◽  
Transverse Relaxation Time ◽  
Cross Sectional Area ◽  
Neck Muscle ◽  
Upright Posture ◽  
Sectional Area ◽  
Cross Sectional ◽  
Transverse Relaxation ◽  
Muscle Cross Sectional Area

Conley, Michael S., Jeanne M. Foley, Lori L. Ploutz-Snyder, Ronald A. Meyer, and Gary A. Dudley. Effect of acute head-down tilt on skeletal muscle cross-sectional area and proton transverse relaxation time. J. Appl. Physiol.81(4): 1572–1577, 1996.—This study investigated changes in skeletal muscle cross-sectional area (CSA) evoked by fluid shifts that accompany short-term 6° head-down tilt (HDT) or horizontal bed rest, the time course of the resolution of these changes after resumption of upright posture, and the effect of altered muscle CSA, in the absence of increased contractile activity, on proton transverse relaxation time (T2). Average muscle CSA and T2 were determined by standard spin-echo magnetic resonance imaging. Analyses were performed on contiguous transaxial images of the neck and calf. After a day of normal activity, 24 h of HDT increased neck muscle CSA 19 ± 4 (SE)% ( P < 0.05) while calf muscle CSA decreased 14 ± 3% ( P < 0.05). The horizontal posture (12 h) induced about one-half of these responses: an 11 ± 2% ( P < 0.05) increase in neck muscle CSA and an 8 ± 2% decrease ( P < 0.05) in the calf. Within 2 h after resumption of upright posture, neck and calf muscle CSA returned to within 0.5% ( P > 0.05) of the values assessed after a day of normal activity, with most of the change occurring within the first 30 min. No further change in muscle CSA was observed through 6 h of upright posture. Despite these large alterations in muscle CSA, T2 was not altered by more than 1.1 ± 0.6% ( P > 0.05) and did not relate to muscle size. These results suggest that postural manipulations and subsequent fluid shifts modeling microgravity elicit marked changes in muscle size. Because these responses were not associated with alterations in muscle T2, it does not appear that simple movement of water into muscle can explain the contrast shift observed after exercise.

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