Structure of the cortical cytoskeleton in fibers of postural muscles and cardiomyocytes of mice after 30-day 2-g centrifugation

2015 ◽  
Vol 118 (5) ◽  
pp. 613-623 ◽  
Author(s):  
Irina V. Ogneva ◽  
V. Gnyubkin ◽  
N. Laroche ◽  
M. V. Maximova ◽  
I. M. Larina ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Tibialis Anterior ◽  
Mechanical Load ◽  
Tibialis Anterior Muscle ◽  
Muscle Fibers ◽  
Control Group ◽  
Negative Effects ◽  
Transverse Stiffness ◽  
G 12 ◽  
Cortical Cytoskeleton

Altered external mechanical loading during spaceflights causes negative effects on muscular and cardiovascular systems. The aim of the study was estimation of the cortical cytoskeleton statement of the skeletal muscle cells and cardiomyocytes. The state of the cortical cytoskeleton in C57BL6J mice soleus, tibialis anterior muscle fibers, and left ventricle cardiomyocytes was investigated after 30-day 2- g centrifugation (“2- g” group) and within 12 h after its completion (“2- g + 12-h” group). We used atomic force microscopy for estimating cell's transverse stiffness, Western blotting for measuring protein content, and RT-PCR for estimating their expression level. The transverse stiffness significantly decreased in cardiomyocytes (by 16%) and increased in skeletal muscles fibers (by 35% for soleus and by 29% for tibialis anterior muscle fibers) in animals of the 2-g group (compared with the control group). For cardiomyocytes, we found that, in the 2- g + 12-h group, α-actinin-1 content decreased in the membranous fraction (by 27%) and increased in cytoplasmic fraction (by 28%) of proteins (compared with the levels in the 2- g group). But for skeletal muscle fibers, similar changes were noted for α-actinin-4, but not for α-actinin-1. In conclusion, we showed that the different isoforms of α-actinins dissociate from cortical cytoskeleton under increased/decreased of mechanical load.

Highly Purified Hematopoietic Stem Cells Convert to Cells with Myoblast Characteristics before Forming Myotubes.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 396-396
Author(s):  
Mehrdad Abedi ◽  
Deborah A. Greer ◽  
Bethany M. Foster ◽  
Gerald A. Colvin ◽  
Delia A. Demers ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Transgenic Mice ◽  
Tibialis Anterior ◽  
Mononuclear Cells ◽  
Tibialis Anterior Muscle ◽  
Muscle Fibers ◽  
Pcr Analysis ◽  
Hematopoietic Stem ◽  
Marrow Cells

Abstract We have previously shown robust conversion of marrow cells to skeletal muscle (up to 12 percent) in a regenerative environment. We have also recently shown the presence of marrow derived muscle colonies. Evaluation of GFP fluorescent intensity of fibers in individual colonies and comparing them with the single fibers outside the colonies strongly suggests a clonal origin for these colonies. Cotransplantation of marrow cells from Yellow and Cyan Fluorescent Protein transgenic mice also supported this theory. We studied the type of cells responsible for marrow to muscle conversion in an immunocompetent and an immunocomprosied model of marrow transplant. The choice of two models was to clarify any bias related to immunologic reactivity of GFP positive cells that has been well documented in the literature. In the first model, different population of GFP positive marrow cells were transplanted intravenously, after sublethal doses of radiation into C57BL/6 mice. One week after transplant their tibialis anterior muscle were injured with cardiotoxin and their muscles were evaluated for GFP positive, dystrophin positive and CD45 negative muscle fibers. In the second model, different population of GFP positive marrow cells were injected directly into tibilias anterior of Bege/Scid mice one day after cardiotoxin injury. Similar to the first model, GFP positive muscle fibers were evaluated 4 weeks post injury. For each population of marrow cells 3 to 6 animals were transplant with cells either positive or negative for the specific surface markers. Our data demonstrates that conversion potential of marrow cells to skeletal muscle fibers is highly enriched in a CD45 positive, c-Kit positive, Flk-2 positive and Sca-1 positive population. Furthermore, CD34 negative, CXCR4 negative and lineage negative cells have higher potential to participate in marrow to muscle conversion. This indicates that under the conditions of our experiments, mesenchymal stem cells are not the origin of marrow derived GFP muscle fiber. To follow the fate of marrow cells homed into muscle we transplanted GFP marrow cells into radiated C57BL/6 mice and at different timepoints before and after injury, harvested tibialis anterior muscle of these animals. Isolation of mononuclear cells from these samples revealed a new GFP+ CD45 negative population which was very rare at 1 week but more abundant at 4 weeks after transplant. Real time PCR analysis of these cells showed multiple stem cells markers including Sca-1, endoglin, c-Kit and CD34. They did not express any RNA markers for satellite cells or myoblasts (pax 7, MyoD, Myf 5) or hematopoietic cells (CD45, CD11b). We next injured GFP transplanted animals with cardiotoxin and isolated the same CD45-GFP+ population 3 days after injury. Real time PCR analysis at this point showed RNA activity for myoblast including Myf5, MyoD and desmin. Immunofluorescent staining of Lin-, Sca+ cKit+ marrow cells from GFP transgenic mice injected into cardiotoxin injured tibialis anterior muscle of Bege Scid mice confirmed our RT-PCR data and showed the presence of MyoD, Myf5, Myogenin and desmin in donor derived cells in recipient muscle. These data suggests that marrow derived mononuclear cells with hematopoietic stem cell phenotype in the recipient muscle lose their hematopoietic characteristics and obtain myoblast phenomenon after being exposed to injury.

scholarly journals Sarcopenia Diagnosis: Reliability of the Ultrasound Assessment of the Tibialis Anterior Muscle as an Alternative Evaluation Tool

Diagnostics ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2158
Author(s):  
Massimiliano Leigheb ◽  
Alessandro de Sire ◽  
Matteo Colangelo ◽  
Domenico Zagaria ◽  
Federico Alberto Grassi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Muscle Thickness ◽  
Healthy Control Group ◽  
Control Group ◽  
Skeletal Muscle Index ◽  
Healthy Control ◽  
Ultrasound Assessment

Sarcopenia is a skeletal muscle disorder characterized by reduced muscle mass, strength, and performance. Muscle ultrasound can be helpful in assessing muscle mass, quality, and architecture, and thus possibly useful for diagnosing or screening sarcopenia. The objective of this study was to evaluate the reliability of ultrasound assessment of tibialis anterior muscle in sarcopenia diagnosis. We included subjects undergoing total or partial hip replacement, comparing measures with a healthy control group. We measured the following parameters: tibialis anterior muscle thickness, echogenicity, architecture, stiffness, skeletal muscle index (SMI), hand grip strength, and sarcopenia related quality of life evaluated through the SarQoL questionnaire. We included 33 participants with a mean age of 54.97 ± 23.91 years. In the study group we found reduced tibialis anterior muscle thickness compared to the healthy control group (19.49 ± 4.92 vs. 28.94 ± 3.63 mm, p < 0.05) with significant correlation with SarQoL values (r = 0.80, p < 0.05), dynamometer hand strength (r = 0.72, p < 0.05) and SMI (r = 0.76, p < 0.05). Moreover, we found reduced stiffness (32.21 ± 12.31 vs. 27.07 ± 8.04 Kpa, p < 0.05). AUC measures of ROC curves were 0.89 predicting reduced muscle strength, and 0.97 predicting reduced SMI for tibialis anterior muscle thickness, while they were 0.73 and 0.85, respectively, for muscle stiffness. Our findings showed that ultrasound assessment of tibialis anterior muscle might be considered a reliable measurement tool to evaluate sarcopenia.

Effect of Experimentally Induced Chronic Kidney disease on Skeletal, Cardiac and Smooth Muscle fibers of albino rat

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Ghada Lotfy ◽  
Amel Soliman ◽  
Nevine Bahaa ◽  
Mohammed Hegazi
Keyword(s):  
Skeletal Muscle ◽  
Chronic Kidney Disease ◽  
Smooth Muscle ◽  
Kidney Disease ◽  
Intramuscular Injection ◽  
Muscle Fibers ◽  
Lateral Wall ◽  
Control Group ◽  
Once Daily ◽  
Group Ii

Abstract Background Chronic kidney disease (CKD), or chronic renal failure (CRF) as it was historically termed, includes all degrees of decreased renal function, starting from mild, and moderate, to severe chronic kidney failure. Skeletal muscle atrophy frequently complicates the course of CKD and is associated with excess morbidity and mortality. Cardiovascular diseases have been reported to be the leading causes of death in CKD patients. Chronic Kidney Disease was also reported to be associated with an increased incidence of acid-related gastrointestinal disorders. Aim of the work The aim of this study was to investigate the effect of chronic kidney disease experimentally induced by gentamicin intramuscular injection on the histological structure of gastrocnemius skeletal muscle, left ventricular cardiac muscle and smooth muscle fibers of lower esophagus. Materials and methods Twenty male adult Wistar albino rats were randomly and equally divided into two groups. Group I (control group) received physiological saline intramuscular injection, once daily for 28 consecutive days, in a dose equivalent to that taken in group II. Group II (Gentamicin-treated group) were given Gentamicin intramuscular injection for induction of CKD. Gentamicin was given as Gentamycin sulfate, 40 mg/ml (Sandoz, Switzerland), once daily, in a dose of 80 mg/kg/day for 28 days to induce CKD. After 28 days of the first injection of gentamicin, rats were anaesthetized and blood samples were collected to measure the level of serum urea and creatinine. The left kidneys, the middle third of left gastrocnemius muscle, the lateral wall of left ventricle (LV) and the gastroesophageal junction of all rats of both groups (I and II) were processed for light microscopic study. The middle third of left gastrocnemius muscle, the lateral wall of left ventricle (LV) were further processed for transmission electron microscopic study. Histomorphometrical and statistical analysis were also done. Results The LM examination revealed moderate obliteration of glomeruli, dilatation in some renal tubules and collapse in others, mainly in distal convoluted tubules, with significant fibrosis of renal parenchyma. Serum urea and creatinine levels were increased significantly. The skeletal muscle fibers of the rats in group II (CKD) showed focal areas of myofibers degeneration with siginificant fibrosis. The cardiac muscle fibers of the rats in the group II (CKD) showed focal areas of cardiomyocytes degeneration and other areas of significantly hypertrophied fibers. The smooth muscle fibers of the lower esophageal sphincter of the rats in group II (CKD) showed no significant structural changes compared with the control group, however, the myenetric plexus showed multiple pyknotic and karyolitic nuclei with vacuolated cytoplasm. In addition, insignificant increase in the amount of collagen fibers was observed in almost all layers. Conclusion CKD produced moderate atrophy of skeletal muscle fibers, significant increase in the cardiomyocyte size and no significant structural effect of smooth muscle fibers of the lower esophageal sphincter.

scholarly journals Imobilização articular: efeitos sobre o tecido muscular de camundongos obesos e desnutridos

2016 ◽  
Vol 18 (1) ◽  
pp. 1 ◽  
Author(s):  
Renato Rissi ◽  
George Azevedo Lemos ◽  
Bernardo Neme Ide ◽  
Rafael Ludemann Camargo ◽  
Renato Chaves Souto Branco ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Tibialis Anterior ◽  
Muscle Fibers ◽  
Musculoskeletal Injuries ◽  
Control Group ◽  
Adhesive Tape ◽  
Male Mice ◽  
Histomorphometric Analysis ◽  
Short Period ◽  
Malnourished Group

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n1p1 Although it is a widely used resource for the treatment of musculoskeletal injuries, immobilization causes deleterious effects in muscle tissue after a short period of time. This study aimed to evaluate the gastrocnemius and tibialis anterior muscles of obese and protein malnourished animals under joint immobilization condition. Overall, 28 adult male mice were used (C57 / BL6), being divided into four groups (N = 7): Control Group (CG), Immobilized Control Group (ICG), Immobilized Obese Group (IOG) and Immobilized Malnourished Group (IMG). The immobilization protocol was performed by the use of adhesive tape and plaster. The conditions and obesity and protein malnutrition have been developed through the ingestion of diets specific for each group of animals. The histomorphometric analysis of muscles evaluated area and the diameter of muscle fibers. All immobilized groups showed reduction in the area and diameter of muscle fibers when compared to GC. Comparisons among immobilized groups showed that the area and diameter of muscle fibers of IOG and IMG were lower than ICG. The immobilization protocol caused reduction in muscle trophism in animals, and obese and malnourished animals suffered high losses under condition of muscle atrophy. 

STIMULATION OF RAT SKELETAL MUSCLE ANGIOGENESIS BY DIRECT AND CELL-MEDIATED ADMINISTRATION OF RECOMBINANT ANGIOGENIN GENE

2020 ◽  
pp. 35-40
Author(s):  
И. В. Саматошенков
Keyword(s):  
Skeletal Muscle ◽  
Gastrocnemius Muscle ◽  
Mononuclear Cells ◽  
Muscle Fibers ◽  
Control Group ◽  
Human Umbilical Cord Blood ◽  
Human Umbilical Cord ◽  
Ischemic Area ◽  
Serotype 5 ◽  
Genetic Constructs

Цель - оценить эффективность реваскуляризации икроножной мышцы крысы в условиях прямой и опосредованной мононуклеарными клетками крови пуповины человека (МККП) доставки в область ишемии рекомбинантного гена ангиогенина (Ang) человека при помощи аденовирусного вектора 5-го серотипа (Ad5). Материал и методы. Исследования проведены на 30 крысах линии Wistar. Через 14 сут после иссечения фрагмента бедренной артерии животным инъецировали в ишемизированную икроножную мышцу генетическую конструкцию (группа Ad5-Ang, n=15). Крысам другой группы (МККП+Ad5-Ang, n=15) в тот же срок трансген доставляли в мышцу при помощи МККП. В группе контроля животным (n=15) вводили в мышцу 0,9 % NaCl в тех же условиях. Через 14 и 28 сут в области ишемии оценивали отношение капилляры/мышечные волокна, количество мышечных волокон и количество мышечных волокон с центральным расположением ядер (МЦЯ). Капилляры идентифицировали по локализации эндотелиальных клеток, выявляемых при помощи иммуногистохимической реакции с антителами против CD31. Результаты. На 14-е сутки после введения МККП+Ad5-Ang показатель отношения количества капилляров к количеству мышечных волокон в области ишемии увеличивается на 57 % (p<0,05). На 28-е сутки в группе МККП+Ad5-Ang и в группе Ad5-Ang значимые различия по данному показателю при сравнении с контрольной группой не выявлены. Количество мышечных волокон на 14-е сутки в группе Ad5-Ang не изменяется, а в группе МККП+Ad5-Ang - уменьшается на 58,4 % (p<0,05). К 28-м суткам этот показатель в группе МККП+Ad5-Ang уменьшается на 95,9 % (p<0,05), а в группе Ad5-Ang - на 197,8 % (p<0,05). Количество МЦЯ существенно увеличивается в обеих экспериментальных группах с применением генетических конструкций на 14-е сутки. Выводы. Введение рекомбинантного гена Ang в область ишемии скелетной мышцы или его доставка в эту область при помощи мононуклеарных клеток крови пуповины стимулирует ангиогенез и постишемическую регенерацию мышечных волокон. Objective - to evaluate the effectiveness of revascularization of the rat gastrocnemius muscle following direct and human umbilical cord blood mononuclear cells (MNCs)-mediated delivery of human recombinant angiogenin (Ang) gene to the ischemic area using adenovirus serotype 5 vector (Ad5). Materials and methods. The study was carried out on 30 Wistar rats. Fourteen days after the excision of the femoral artery fragment, the genetic construct was injected into the animals’ ischemic gastrocnemius muscle (AD5-Ang group, n=15). In the other group (mccp+Ad5-Ang, n=15), the transgene was delivered to the muscle with the help of MNCs within the same time limit. In the control group (n=15) 0,9 % NaCl was injected into the muscle of animals under the same conditions. Fourteen and twenty-eight days after the injection, the ratio of capillaries/muscle fibers, the number of muscle fibers and the number of muscle fibers with a central location of nuclei (MCN) were evaluated in the ischemic area. Capillaries were identified by localization of endothelial cells detected by immunohistochemical reaction with antibodies against CD31. Results. On the 14th day after administration of MNCs+Ad5Ang, the ratio of capillaries to the number of muscle fibers in the ischemic area increased by 57 % (p<0,05). On the 28th day in the MNCs+Ad5-Ang group and in the Ad5-Ang group, no significant differences in this indicator were found compared with the control group. The number of muscle fibers on the 14 day in the Ad5-Ang group did not change, and in the MNCs+Ad5-Ang group, it decreased by 58,4 % (p<0,05). By the 28th day, this indicator in the MNCs+Ad5-Ang group decreased by 95,9 % (p<0,05), and in the Ad5-Ang group - by 197,8 % (p<0,05). The number of MCN on the 14 day significantly increased in both experimental groups, in which the genetic constructs were used. Conclusion. The introduction of recombinant ang gene into the area of skeletal muscle ischemia or its delivery to this area with the help of MCNs stimulates angiogenesis and post-ischemic regeneration of muscle fibers.

scholarly journals Arrdc2 and Arrdc3 elicit divergent changes in gene expression in skeletal muscle following anabolic and catabolic stimuli

2019 ◽  
Vol 51 (6) ◽  
pp. 208-217 ◽  
Author(s):  
Bradley S. Gordon ◽  
Michael L. Rossetti ◽  
Alexey M. Eroshkin
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Tibialis Anterior ◽  
Gene Networks ◽  
Tibialis Anterior Muscle ◽  
The Body ◽  
Molecular Networks ◽  
Expression Of Genes ◽  
Consistent Change ◽  
Mechanical Overload

Skeletal muscle is a highly plastic organ regulating various processes in the body. As such, loss of skeletal muscle underlies the increased morbidity and mortality risk that is associated with numerous conditions. However, no therapies are available to combat the loss of muscle mass during atrophic conditions, which is due in part to the incomplete understanding of the molecular networks altered by anabolic and catabolic stimuli. Thus, the current objective was to identify novel gene networks modulated by such stimuli. For this, total RNA from the tibialis anterior muscle of mice that were fasted overnight or fasted overnight and refed the next morning was subjected to microarray analysis. The refeeding stimulus altered the expression of genes associated with signal transduction. Specifically, expression of alpha arrestin domain containing 2 (Arrdc2) and alpha arrestin domain containing 3 (Arrdc3) was significantly lowered 70–85% by refeeding. Subsequent analysis showed that expression of these genes was also lowered 50–75% by mechanical overload, with the combination of nutrients and mechanical overload acting synergistically to lower Arrdc2 and Arrdc3 expression. On the converse, stimuli that suppress growth such as testosterone depletion or acute aerobic exercise increased Arrdc2 and Arrdc3 expression in skeletal muscle. While Arrdc2 and Arrdc3 exhibited divergent changes in expression following anabolic or catabolic stimuli, no other member of the Arrdc family of genes exhibited the consistent change in expression across the analyzed conditions. Thus, Arrdc2 and Arrdc3 are a novel set of genes that may be implicated in the regulation of skeletal muscle mass.

scholarly journals Effect of Electroacupuncture on the Expression of Agrin and Acetylcholine Receptor Subtypes in Rats with Tibialis Anterior Muscular Atrophy Induced by Sciatic Nerve Injection Injury

2017 ◽  
Vol 35 (4) ◽  
pp. 268-275 ◽  
Author(s):  
Jianqi Yu ◽  
Meng Wang ◽  
Junying Liu ◽  
Xiaoming Zhang ◽  
Shengbo Yang
Keyword(s):  
Sciatic Nerve ◽  
Protein Expression ◽  
Muscle Fibre ◽  
Acetylcholine Receptor ◽  
Muscle Atrophy ◽  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Control Group ◽  
Receptor Subtypes ◽  
Injection Injury

Objective To investigate the effects of electroacupuncture (EA) on mRNA and protein expression of agrin, acetylcholine receptor (AChR)-ε and AChR-γ in a rat model of tibialis anterior muscle atrophy induced by sciatic nerve injection injury, and to examine the underlying mechanism of action. Methods Fifty-four adult Sprague-Dawley rats were divided into four groups: healthy control group (CON, n=6); sciatic nerve injury group (SNI, n=24), comprising rats euthanased at 1, 2, 4 and 6 weeks, respectively, after penicillin injection-induced SNI (n=6 each); CON+EA group (n=12), comprising healthy rats euthanased at 4 and 6 weeks (after 2 and 4 weeks, respectively, of EA at GB30 and ST36); and SNI+EA group, comprising rats euthanased at 4 and 6 weeks (after 2 and 4 weeks, respectively, of EA). The sciatic nerve functional index (SFI), tibialis anterior muscle weight, muscle fibre cross-sectional area (CSA), and changes in agrin, AChR-ε, and AChR-γ expression levels were analysed. Results Compared with the control group (CON), SNI rats showed decreased SFI. The weight of the tibialis anterior muscle and muscle fibre CSA decreased initially and recovered slightly over time. mRNA/protein expression of agrin and AChR-ε were downregulated and AChR-γ expression was detectable (vs zero expression in the CON/CON+EA groups). There were no significant differences in CON+EA versus CON groups. However, the SNI+EA group exhibited significant improvements compared with the untreated SNI group (p<0.05). Conclusions EA may alleviate tibialis anterior muscle atrophy induced by sciatic nerve injection injury by upregulating agrin and AChR-ε and downregulating AChR-γ.

Spectral Analysis of Heart Rate Variability during Trigger Point Acupuncture

2014 ◽  
Vol 32 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Yoji Kitagawa ◽  
Kenichi Kimura ◽  
Sohei Yoshida
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Spectral Analysis ◽  
Tibialis Anterior ◽  
Trigger Point ◽  
Tibialis Anterior Muscle ◽  
Trigger Points ◽  
Control Group ◽  
The Right

Objectives To clarify changes in the cardiovascular autonomic nervous system function due to trigger point acupuncture, we evaluated differences in responses between acupuncture at trigger points and those at other sites using spectral analysis of heart rate variability. Methods Subjects were 35 healthy men. Before measurements began the subjects were assigned to a trigger point acupuncture or control group based on the presence/absence of referred pain on applying pressure to a taut band within the right tibialis anterior muscle. The measurements were conducted in a room with a temperature of 25°C, with subjects in a long sitting position after 10 min rest. Acupuncture needles were retained for 10 min at two sites on the right tibialis anterior muscle. ECG was performed simultaneously with measurements of blood pressure and the respiratory cycle. Based on the R–R interval on the ECG, frequency analysis was performed, low-frequency (LF) and high-frequency (HF) components were extracted and the ratio of LF to HF components (LF/HF) was evaluated. Results The trigger point acupuncture group showed a transient decrease in heart rate and an increase in the HF component but no significant changes in LF/HF. In the control group, no significant changes were observed in heart rate, the HF component or LF/HF. There were no consistent changes in systolic or diastolic blood pressure in either group. Conclusions These data suggest that acupuncture stimulation of trigger points of the tibialis anterior muscle transiently increases parasympathetic nerve activity.

scholarly journals Age Dependent Modification of the Metabolic Profile of the Tibialis Anterior Muscle Fibers in C57BL/6J Mice

2020 ◽  
Vol 21 (11) ◽  
pp. 3923
Author(s):  
Emiliana Giacomello ◽  
Emanuela Crea ◽  
Lucio Torelli ◽  
Alberta Bergamo ◽  
Carlo Reggiani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Expression ◽  
Tibialis Anterior ◽  
Skeletal Muscles ◽  
Tibialis Anterior Muscle ◽  
Morphological Characteristics ◽  
Oxidative Capacity ◽  
Essential Information ◽  
Metabolic Properties ◽  
Architectural Organization

Skeletal muscle aging is accompanied by mass reduction and functional decline, as a result of multiple factors, such as protein expression, morphology of organelles, metabolic equilibria, and neural communication. Skeletal muscles are formed by multiple fibers that express different Myosin Heavy Chains (MyHCs) and have different metabolic properties and different blood supply, with the purpose to adapt their contraction to the functional need. The fine interplay between the different fibers composing a muscle and its architectural organization determine its functional properties. Immunohistochemical and histochemical analyses of the skeletal muscle tissue, besides evidencing morphological characteristics, allow for the precise determination of protein expression and metabolic properties, providing essential information at the single-fiber level. Aiming to gain further knowledge on the influence of aging on skeletal muscles, we investigated the expression of the MyHCs, the Succinate Dehydrogenase (SDH) activity, and the presence of capillaries and Tubular Aggregates (TAs) in the tibialis anterior muscles of physiologically aging C57BL/6J mice aged 8 (adult), 18 (middle aged), and 24 months (old). We observed an increase of type-IIB fast-contracting fibers, an increase of the oxidative capacity of type-IIX and -IIA fibers, a general decrease of the capillarization, and the onset of TAs in type-IIB fibers. These data suggest that aging entails a selective modification of the muscle fiber profiles.

Skeletal muscle fiber composition is related to adiposity and in vitro glucose transport rate in humans

1995 ◽  
Vol 268 (3) ◽  
pp. E453-E457 ◽  
Author(s):  
M. S. Hickey ◽  
J. O. Carey ◽  
J. L. Azevedo ◽  
J. A. Houmard ◽  
W. J. Pories ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Muscle Fiber ◽  
Muscle Fibers ◽  
Skeletal Muscle Fiber ◽  
Transport Rate ◽  
Control Group ◽  
Type I ◽  
Fiber Composition

The purpose of this study was to determine if a relationship exists among skeletal muscle fiber composition, adiposity, and in vitro muscle glucose transport rate in humans. Rectus abdominus muscle was obtained during elective abdominal surgery from nonobese control (n = 12), obese (n = 12), and obese non-insulin-dependent diabetes mellitus (NIDDM) patients (n = 10). The obese NIDDM group had a significantly lower percentage of type I muscle fibers (32.2 +/- 1.9%) than the obese group (40.4 +/- 2.7%), and both obese groups were significantly lower than the control group (50.0 +/- 2.6%). Insulin-stimulated glucose transport, determined on 28 subjects, was significantly lower in both the obese (3.83 +/- 0.48 nmol.min-1.mg-1) and NIDDM (3.93 +/- 1.0 nmol.min-1.mg-1) groups vs. the control group (7.35 +/- 1.50 nmol.min-1.mg-1). Body mass index (BMI) was inversely correlated to percent type I fibers (r = -0.50, P < 0.01) and to the insulin-stimulated glucose transport rate (r = -0.53, P < 0.01). The percentage of type I muscle fibers was related to the insulin-stimulated glucose transport rate (r = 0.57, P < 0.01), although this relationship was not significant after adjusting for BMI. Although these data do not support an independent relationship between fiber type and insulin action in obesity, a reduced skeletal muscle type I fiber population may be one component of a multifactorial process involved in the development of insulin resistance.

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