Human vastus lateralis and soleus muscles display divergent cellular contractile properties

The purpose of this study was to investigate potential differences in single-fiber contractile physiology of fibers with the same myosin heavy chain isoform (MHC I and MHC IIa) originating from different muscles. Vastus lateralis (VL) and soleus biopsies were obtained from 27 recreationally active females (31 +/- 1 yr, 59 +/- 1 kg). A total of 943 single fibers (MHC I = 562; MHC IIa = 301) were isolated and examined for diameter, peak tension (Po), shortening velocity (Vo), and power. The soleus had larger (P < 0.05) fibers (MHC I +18%; MHC IIa +19%), higher MHC I Vo (+13%), and higher MHC I Po (+18%) compared with fibers from the VL. In contrast, fibers from the VL had higher (P < 0.05) specific tension (MHC I +18%; MHC IIa +20%), and MHC I normalized power (+25%) compared with the soleus. There was a trend for MHC IIa soleus fibers to have higher Vo [MHC IIa +13% (P = 0.058)], whereas VL MHC IIa fibers showed a trend for higher normalized power compared with soleus fibers [MHC IIa +33% (P = 0.079)]. No differences in absolute power were detected between muscles. These data highlight muscle-specific differences in single-fiber contractile function that should serve as a scientific basis for consideration when extending observations of skeletal muscle tissue from one muscle of interest to other muscles of origin. This is important when examining skeletal muscle adaptation to physical states such as aging, unloading, and training.     

Buffering capacity of deproteinized human vastus lateralis muscle

The in vitro deproteinized vastus lateralis muscle buffer capacity, carnosine, and histidine levels were examined in 20 men from 4 distinct populations (5 sprinters, 800-m runners; 5 rowers; 5 marathoners; 5 untrained). Needle biopsies were obtained at rest from the vastus lateralis muscle. The buffer capacity was determined in deproteinized homogenates by repeatedly titrating supernatant extracts over the pH range of 7.0-6.0 with 0.01 N HCl. Carnosine and histidine levels were determined on an amino acid AutoAnalyzer. Fast-twitch fiber percentage was determined by staining intensity of myosin adenosinetriphosphatase. High-intensity running performance was assessed on an inclined treadmill run to fatigue (20% incline; 3.5 m X s-1). Significantly (P less than 0.01) elevated buffer capacities, carnosine levels, and high-intensity running performances were demonstrated by the sprinters and rowers, but no significant differences existed between these variables for the marathoners vs. untrained subjects. Low but significant (P less than 0.05) interrelationships were demonstrated between buffer capacity, carnosine levels, and fast-twitch fiber composition. These findings indicate that the sprinters and rowers possess elevated buffering capabilities and carnosine levels compared with marathon runners and untrained subjects.     

Torque-velocity characteristics and muscle fiber type in human vastus lateralis

The relationship between torque-velocity characteristics of the knee extensors during isokinetic contractions and muscle fiber type of the vastus lateralis, determined from two muscle biopsy samples, was investigated in 12 male and 18 female subjects. Peak torque, corrected for the effect of gravity and impact artifact, was classified as corrected peak torque. The torque measured 30 degrees from full extension and, corrected for gravity, was classified as corrected torque at 30 degrees. No significant correlations were found between the percentage of fast-twitch fibers (%FT) or the relative area of FT fibers (%FTA) and corrected peak torque values for any of the velocities tested or the knee angles where corrected peak torques were measured. However, significant inverse relationships were determined for corrected torque at 30 degrees at all but the fastest velocity (270 degrees/s) and both %FT and %FTA for the male subjects. These results reveal that muscle fiber type of the vastus lateralis, based on duplicate muscle samples, is not related to the peak torque actually generated by the knee extensors but may influence the shape of the torque output for maximal contractions sustained over the entire range of motion.     

Regenerative defect in vastus lateralis muscle of patients with chronic obstructive pulmonary disease

Background

Impaired skeletal muscle regeneration could contribute to the progression of muscle atrophy in patients with chronic obstructive pulmonary disease (COPD).

Methods

Satellite cells and myogenesis-related proteins were compared between healthy subjects and patients with COPD, with or without muscle atrophy. Satellite cells were isolated and cultured to assess their proliferative and differentiation aptitudes.

Results

Although satellite cell numbers in muscle samples were similar between groups, the proportion of muscle fibers with central nuclei was increased in COPD. In muscle homogenates, increased expression of MyoD and decreased expression of myogenin and MRF4 were observed in COPD. In cultured satellite cells of patients with COPD, increased protein content was observed for Pax7, Myf5 (proliferation phase) and myogenin (differentiation phase) while myosin heavy chain protein content was significantly lower during differentiation.

Conclusion

In COPD, the number of central nuclei was increased in muscle fibers suggesting a greater number of attempts to regenerate muscle tissue than in healthy subjects. Myogenesis signaling was also altered in muscle homogenates in patients with COPD and there was a profound reduction in the differentiation potential in this population as indicated by a reduced ability to incorporate myosin heavy chain into newly formed myotubes. Collectively, these results indicate that skeletal muscle regenerative capacity termination is impaired in COPD and could contribute to the progression of muscle atrophy progression in this population.     

Electromechanical delay in the vastus lateralis muscle during dynamic isometric contractions

Electromechanical delay (EMD) values were obtained using a cross-correlation technique for a series of 14 repetitive submaximal dynamic isometric contractions of the vastus lateralis performed by five subjects. To avoid a phase lag, which is introduced with one-way filtering, the EMG was processed with a bi-directional application of a second-order Butterworth filter. A mean EMD value of 86 ms (SD = 5.1 ms) was found. Moreover, contraction and relaxation delays were computed and compared. There was a significant difference between the contraction and relaxation delays (P less than 0.005). The mean contraction delay was 81.9 ms and the mean relaxation delay was 88.8 ms. Despite this significant difference, the computed contraction and relaxation delay values lie in the same range as the total phase lag, calculated with the cross-correlation technique. The magnitude of EMD values found supports the need to account for this delay when interpreting temporal aspects of patterns of intermuscular coordination.     

Label-free Quantitative Protein Profiling of vastus lateralis Muscle During Human Aging

Sarcopenia corresponds to the loss of muscle mass occurring during aging, and is associated with a loss of muscle functionality. Proteomic links the muscle functional changes with protein expression pattern. To better understand the mechanisms involved in muscle aging, we performed a proteomic analysis of Vastus lateralis muscle in mature and older women. For this, a shotgun proteomic method was applied to identify soluble proteins in muscle, using a combination of high performance liquid chromatography and mass spectrometry. A label-free protein profiling was then conducted to quantify proteins and compare profiles from mature and older women. This analysis showed that 35 of the 366 identified proteins were linked to aging in muscle. Most of the proteins were under-represented in older compared with mature women. We built a functional interaction network linking the proteins differentially expressed between mature and older women. The results revealed that the main differences between mature and older women were defined by proteins involved in energy metabolism and proteins from the myofilament and cytoskeleton. This is the first time that label-free quantitative proteomics has been applied to study of aging mechanisms in human skeletal muscle. This approach highlights new elements for elucidating the alterations observed during aging and may lead to novel sarcopenia biomarkers.A gradual degenerative loss of skeletal muscle mass and function is one of the most consistent hallmarks of normal aging. When it reaches defined thresholds, this condition is referred to as sarcopenia (1, 2), and can be associated with disability, poor quality of life, frailty, and increased mortality (3). Aging impacts the morphology, function and biochemical properties of skeletal muscle, but the mechanisms leading to the changes in muscle tissue remain unclear.Proteomics links the muscle functional changes with the protein expression pattern. Several proteomic approaches have already been used to study sarcopenia. Protein profiling of whole tissue homogenates has been performed using two-dimensional gel electrophoresis (2DGE)¹ and mass spectrometry to identify the proteins differentially expressed during aging in rat (4–6) and human muscle (7, 8). Other studies have focused on specific fractions such as mitochondrial proteins (9), phosphoproteins (10), glycoproteins (11), basic proteins (12), or calpain interacting proteins (13). The few proteomic studies available on human skeletal muscle are mostly based on the 2DGE approach, which implies focusing on a specific pH range (7, 8). Despite its power of high-resolution, 2DGE presents a limited dynamic range and scarcely resolves low abundance regulatory proteins, hydrophobic proteins, and proteins with extreme pI and/or M_r (14).To circumvent these limitations, we propose in the present study to apply a label-free protein profiling based on a shotgun proteomics approach. This technique permits to identify proteins in a complex mixture after trypsin hydrolysis, using a combination of high performance liquid chromatography and mass spectrometry. In a shotgun analysis previously performed on whole muscle extracts, the major isoforms of myosin heavy-chain comprise ∼42% of the total spectra (15). Because these major isoforms may hamper identification of other proteins, we decided to precipitate myofibrils at low ionic strength (16, 17) and to focus on the soluble fraction. In this paper, we present the analytical steps of label-free quantitation, which resulted in the identification and quantitation of 255 muscle proteins common to all ten individuals. The comparison of protein profiling between mature and older women highlighted 35 differentially expressed proteins during aging, 25 proteins that have not previously been related to muscle aging. The functional interactions network linking these proteins showed that the two main biological processes were represented by proteins involved in energy metabolism and contractile proteins.     

Electromyography activity of vastus lateralis muscle during whole-body vibrations of different frequencies

The aim of this study was to analyze electromyography (EMG) responses of vastus lateralis muscle to different whole-body vibration frequencies. For this purpose, 16 professional women volleyball players (age, 23.9 +/- 3.6 years; height, 182.5 +/- 11.1 cm; weight, 78.4 +/- 5.6 kg) voluntarily participated in the study. Vibration treatment was administered while standing on a vibrating platform with knees bent at 100 degrees (Nemes Bosco-system, Rome, Italy). EMG root mean square (rms) and was recorded for 60 seconds while standing on the vibrating plate in the following conditions: no vibrations and 30-, 40-, and 50-Hz vibration frequencies in random order. The position was kept for 60 seconds in each treatment condition. EMGrms was collected from the vastus lateralis muscle of the dominant leg. Statistical analysis showed that, in all vibration conditions, average EMGrms activity of vastus lateralis was higher than in the no-vibration condition. The highest EMGrms was found at 30 Hz, suggesting this frequency as the one eliciting the highest reflex response in vastus lateralis muscle during whole-body vibrations in half-squat position. An extension of these studies to a larger population appears worthwhile to further elucidate the responsiveness of the neuromuscular system to whole-body vibrations administered through vibrating platforms and to be able to develop individual treatment protocols.     

The free vastus lateralis flap: an anatomic study with case reports.

The suitability of the thigh as a donor site for a new free flap was examined in 100 cadavers. It was found that the vastus lateralis muscle can be used to form a myocutaneous or fasciomuscular flap, the raising of which causes no technical problems and leads to no functional and only minor aesthetic impairments. Depending on the muscle segment from which the flap is raised, a neurovascular pedicle measuring between 8 and 20 cm with a diameter of 2 to 2.5 mm (artery) or 2.5 to 4 mm (vein) can be formed. The skin island in the myocutaneous flap measures on average 8 x 16 cm and is located above the middle portion of the muscle. The diameter of the supplying perforator vessel is between 0.7 and 1.2 mm. The flap can be raised parallel to head and neck surgery and applied as a myocutaneous flap for coverage of extensive or perforating defects or intraorally as a fasciomuscular flap.     

Glucose and amino acid metabolism in an established line of skeletal muscle cells

The suitability of an established myogenic line (L₆) for the study of skeletal muscle intermediary metabolism was investigated. Myoblasts were grown in tissue culture for ten days at which time they had differentiated into multinucleated myotubes. Myotube preparations were then incubated for up to 96 hours in 10 ml of Dulbecco's modified Eagle medium containing 10% fetal calf serum. Glucose was utilized at a nearly linear rate, 3.0 nmol/min/mg protein. Intracellular glucose was detectable throughout the incubation, even when medium glucose was as low as 16 mg%. During the initial 28 hours of incubation, when net lactate production was observed, only 35% of the glucose utilized was converted to lactate. Alanine was produced in parallel to lactate at an average rate of 0.6 nmol/min/mg protein. In concert with active glutamine utilization, high rates of ammoniagenesis were observed as medium glutamine decreased from 3.3 mM to 0.49 mM and medium ammonia increased from 2.3 mM to 6.2 mM, between zero time and 96 hours of incubation, respectively. The cells maintained stable ATP and citrate levels, and physiologic intracellular lactate/pyruvate ratios (10–24) throughout 96 hours of incubation. These results suggest (1) glucose utilization by skeletal muscle in tissue culture is limited by phosphorylation, not transport; (2) as much as 50% of glucose-derived pyruvate enters mitochondrial pathways; (3) glutamine carbon may be utilized simultaneously with glucose consumption and this process accounts for high rates of ammoniagenesis.     

Capillary density and capillary-to-fibre ratio in vastus lateralis muscle of untrained and trained men

Muscle fibre profile area (Af), volume density (Vv), capillary-to-fibre ratio (CF) and number of capillaries per fibre square millimetre (CD) were determined from needle biopsies of vastus lateralis of twenty-four male volunteers (mean +/- SD: age 25.4+/-5.8 years, height 178.6+/-5.5 cm, body mass 72.1+/-7.7 kg) of different training background. Seven subjects were untrained students (group A), nine were national and sub-national level endurance athletes (group B) with the background of 7.8+/-2.9 years of specialised training, and eight subjects were sprint-power athletes (group C) with 12.8+/-8.7 years of specialised training. Muscle biopsies of vastus lateralis were analysed histochemically for mATPase. Capillaries were visualized and counted using CD31 antibodies against endothelial cells. There were significant differences in the Vv of type I and type II muscle fibres in both trained groups, B (51.8%; 25.6%) and C (50.5%; 26.4%). However, in untrained group A that was treated as a reference group, the difference between Vv of type I and type II fibres was less prominent, nevertheless statistically significant (42.1%; 35.1%). There was also a significant difference in CF: 1.9 in group A and 2.1 in groups B and C. The number of capillaries per mm2 (CD) was 245 (group A), 308 (group B) and 325 (group C). Significant differences (P<0.05) in CF and CD, were found only between group A (1.9; 245) and both groups of trained men, B and C (2.1; 308 and 325). However, endurance athletes (group B), such as long-distance runners, cyclists and cross country skiers, did not differ from the athletes representing short term, high power output sports (group C) such as ice hockey, karate, ski-jumping, volleyball, soccer and modern dance.     

The influence of 5 weeks of ULLS and resistance exercise on vastus lateralis and soleus myosin heavy chain distribution

We examined the distribution of the myosin heavy chain (MHC) isoforms (I, IIa, IIx) of the leg muscles of three groups of men and women (40 +/- 8y) that completed unilateral lower limb suspension only (ULLS), ULLS plus resistance exercise (ULLS+RE), or RE only (RE) for 5 weeks. Muscle biopsies were obtained pre and post from the vastus lateralis of all three groups and the soleus of the ULLS group. Distributions of all three MHC isoforms in the vastus lateralis were unchanged (p<0.05) from pre to post with ULLS. The soleus muscle, which contained no measurable IIx isoform, was also unchanged (p< 0.05) from pre to post ULLS. These results suggest that the percent distribution of the MHC isoforms per unit muscle protein in both the vastus lateralis and soleus does not change during the first five weeks of simulated microgravity. Further, resistance exercise during five weeks of ULLS or ambulation does not appear to alter the MHC distribution per unit muscle protein of the vastus lateralis.     

Reliability of an electrophoretic and image processing analysis of human skeletal muscle taken from m. vastus lateralis

The relative content of myosin heavy chain (MHC) isoforms IIb, IIa and I in human skeletal muscle taken from the m. vastus lateralis of 30 healthy male subjects was analysed using mini-gel electrophoresis. Repeated electrophoretic gels utilizing the same methods were produced for all subjects and the determination of MHC protein bands was performed using a digital scanner and National Institutes of Health (NIH) Image software and laser densitometry. A comparison between the NIH Image processing technique and laser densitometry revealed differences of 6.47%, 6.35% and 6.84% between these measurement techniques for MHC-IIb, -IIa and -I isoforms, respectively. The percentage technical error of measurement (TEM%) between electrophoretic gels was shown to be 19.1%, 17.8% and 14.2%, with regard to percentage of occurrence of MHC-IIb, -IIa and -I isoforms respectively. The variation in electrophoretic gel analyses was shown to be 5.7%, 7.3% and 5.5%, with regard to the percentage of MHC-IIb, -IIa and -I isoforms respectively. Intra-class correlations comparing NIH Image and laser densitometry produced r values in the range 0.38–0.63. Comparisons between and within gel analyses produced r values in the range 0.59–0.94 and 0.93–0.98, respectively. Analyses of variance revealed no significant differences (P < 0.05) between analysis techniques, between␣gels or within gels for the measurement of MHC-IIb, -IIa and -I isoforms. The inter-gel error between fibre subgroups was moderate for the two type-II MHC populations and less for type-I MHC; the intra-individual error in the measuring technique used for classifying the MHC-IIb, -IIa and -I protein bands was small. The results obtained in this investigation showed consistent trends which may reflect a false classification of the type-II MHC populations for the inter-gel and intra-individual analyses. The NIH Image software and digitizing process was shown to be a valid and reliable method for distinguishing between MHC protein bands of human skeletal tissue as separated by mini-gel electrophoretic techniques. Accepted: 6 January 1997     

Use of vastus lateralis muscle flap for repair of trochanteric pressure sores.

The use of a vastus lateralis muscle flap is suggested as an approach to the surgical repair of trochanteric pressure sores in paraplegic patients. The details of the anatomy of the muscle are outlined, and our surgical technique for its use is described.     

Fiber type composition of the vastus lateralis muscle of young men and women.

This study presents data collected over the past 10 years on the muscle fiber type composition of the vastus lateralis muscle of young men and women. Biopsies were taken from the vastus lateralis muscle of 55 women (21.2+/-2.2 yr) and 95 men (21.5+/-2.4 yr) who had volunteered to participate in various research projects. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were classified using mATPase histochemistry, and cross-sectional area was measured for the major fiber types (I, IIA, and IIB). Myosin heavy chain (MHC) content was determined electrophoretically on all of the samples from the men and on 26 samples from the women. With the exception of fiber Type IC, no significant differences were found between men and women for muscle fiber type distribution. The vastus lateralis muscle of both the men and women contained approximately 41% I, 1% IC, 1% IIC, 31% IIA, 6% IIAB, and 20% IIB. However, the cross-sectional area of all three major fiber types was larger for the men compared to the women. In addition, the Type IIA fibers were the largest for the men, whereas the Type I fibers tended to be the largest for the women. Therefore, gender differences were found with regard to the area occupied by each specific fiber type: IIA>I>IIB for the men and I>IIA>IIB for the women. These data establish normative values for the mATPase-based fiber type distribution and sizes in untrained young men and women.     

Regional muscle oxygenation differences in vastus lateralis during different modes of incremental exercise

Background

Near infrared spectroscopy (NIRS) is used to assess muscle oxygenation (MO) within skeletal muscle at rest and during aerobic exercise. Previous investigations have used a single probe placement to measure MO during various forms of exercise. However, regional MO differences have been shown to exist within the same muscle which suggests that different areas of the same muscle may have divergent MO. Thus, the aim of this study was to examine whether regional differences in MO exist within the same muscle during different types of incremental (rest, 25, 50, 75, 100 % of maximum) exercise (1 leg knee extension (KE), 2 leg KE, or cycling).

Methods

Nineteen healthy active males (Mean ± SD: Age 27 ± 4 yrs; VO_2max: 55 ± 11 mL/kg/min) performed incremental exercise to fatigue using each mode of exercise. NIRS probes were placed on the distal and proximal portion of right leg vastus lateralis (VL). Results were analyzed with a 3-way mixed model ANOVA (probe × intensity × mode).

Results

Differences in MO exist within the VL for each mode of exercise, however these differences were not consistent for each level of intensity. Comparison of MO revealed that the distal region of VL was significantly lower throughout KE exercise (1 leg KE proximal MO – distal MO = 9.9 %; 2 leg KE proximal MO – distal MO = 13 %). In contrast, the difference in MO between proximal and distal regions of VL was smaller in cycling and was not significantly different at heavy workloads (75 and 100 % of maximum).

Conclusion

MO is different within the same muscle and the pattern of the difference will change depending on the mode and intensity of exercise. Future investigations should limit conclusions on MO to the area under assessment as well as the type and intensity of exercise employed.

     

Distally based vastus lateralis muscle flap for coverage of wounds about the knee

The blood supply to the vastus lateralis muscle has been evaluated by dye injection techniques in fresh cadaver dissections. The main dominant blood supply is the descending branch of the lateral femoral circumflex artery. Vascular contributions from distal perforators of the superficial femoral artery, the superior geniculate artery, fill the main vascular pedicle in a retrograde fashion. Latex staining is observed consistently in the proximal third of the muscle. Five patients are presented in whom the distally based vastus lateralis muscle flap was successfully used to cover defects above the knee. Superficial muscle necrosis is a complication of this operation but has not precluded its usefulness. It is anticipated that this flap will be useful in the armamentarium of reconstructive surgeons treating such problematic patients.     

Specific oxidative alterations in vastus lateralis muscle of patients with the diagnosis of chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a poorly understood disease characterized by mental and physical fatigue, most often observed in young white females. Muscle pain at rest, exacerbated by exercise, is a common symptom. Although a specific defect in muscle metabolism has not been clearly defined, yet several studies report altered oxidative metabolism. In this study, we detected oxidative damage to DNA and lipids in muscle specimens of CFS patients as compared to age-matched controls, as well as increased activity of the antioxidant enzymes catalase, glutathione peroxidase, and transferase, and increases in total glutathione plasma levels. From these results we hypothesize that in CFS there is oxidative stress in muscle, which results in an increase in antioxidant defenses. Furthermore, in muscle membranes, fluidity and fatty acid composition are significantly different in specimens from CFS patients as compared to controls and to patients suffering from fibromyalgia. These data support an organic origin of CFS, in which muscle suffers oxidative damage.     

Comparison of the muscle activation pattern for the vastus lateralis before and after an 8-week resistance training program

The purpose of this investigation was to use wavelet analyses and pattern classification techniques to examine potential changes in the joint time–frequency distribution of surface electromyographic (EMG) signals due to an 8-week resistance training program. Thirteen untrained men (mean ± S.D. age = 22.2 ± 4.0 yrs) performed eight separate submaximal isometric muscle actions of the dominant leg extensors in 10% increments from 10 to 80% of the maximum voluntary contraction (MVC). During each muscle action, a monopolar surface EMG signal was detected from the vastus lateralis. All signals were then analyzed with a wavelet analysis designed specifically for EMG signals, and the resulting intensity patterns were classified using pattern classification techniques into their respective pre-training versus post-training categories. The results showed accuracy rates (% of correctly classified patterns) that ranged from approximately 62 to 92%, but these rates did not change consistently with increases in force. In addition, for five of the eight submaximal force levels, the classification was considered to be significantly different from random. Thus, although the differences between the pre- and post-training EMG intensity patterns were not always consistent, our findings did suggest that there is the potential for wavelet analyses and pattern classification techniques to be used to examine neuromuscular adaptations during resistance training.