Calcium-activated force of human muscle fibers following a standardized eccentric contraction

2010 ◽  
Vol 299 (6) ◽  
pp. C1409-C1417 ◽  
Author(s):  
Seung Jun Choi ◽  
Jeffrey J. Widrick
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Mechanical Strain ◽  
Eccentric Contraction ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Specific Force ◽  
Shortening Velocity ◽  
Hybrid Fibers ◽  
Fixed End

Peak Ca2+-activated specific force (force/fiber cross-sectional area) of human chemically skinned vastus lateralis muscle fiber segments was determined before and after a fixed-end contraction or an eccentric contraction of standardized magnitude (+0.25 optimal fiber length) and velocity (0.50 unloaded shortening velocity). Fiber myosin heavy chain (MHC) isoform content was assayed by SDS-PAGE. Posteccentric force deficit, a marker of damage, was similar for type I and IIa fibers but threefold greater for type IIa/IIx hybrid fibers. A fixed-end contraction had no significant effect on force. Multiple linear regression revealed that posteccentric force was explained by a model consisting of a fiber type-independent and a fiber type-specific component ( r2 = 0.91). Preeccentric specific force was directly associated with a greater posteccentric force deficit. When preeccentric force was held constant, type I and IIa fibers showed identical susceptibility to damage, while type IIa/IIx fibers showed a significantly greater force loss. This heightened sensitivity to damage was directly related to the amount of type IIx MHC in the hybrid fiber. Our model reveals a fiber-type sensitivity of the myofilament lattice or cytoskeleton to mechanical strain that can be described as follows: type IIa/IIx > type IIa = type I. If these properties extend to fibers in vivo, then alterations in the number of type IIa/IIx fibers may modify a muscle's susceptibility to eccentric damage.

In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone

1996 ◽  
Vol 80 (5) ◽  
pp. 1547-1553 ◽  
Author(s):  
P. J. Adnet ◽  
H. Reyford ◽  
B. M. Tavernier ◽  
T. Etchrivi ◽  
I. Krivosic ◽  
...  
Keyword(s):  
Masseter Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Threshold Concentration ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cross Sectional ◽  
Significant Difference ◽  
Maximal Tension

To determine whether a difference in fiber-type caffeine and Ca2+ sensitivities exists between human masseter and vastus lateralis skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers from 13 masseter and 18 vastus lateralis muscles. Caffeine sensitivity was defined as the threshold concentration inducing > 10% of the maximal tension obtained after the fiber was loaded with a 1.6 x 10(-2) mM Ca2+ solution for 30 s. Significant difference in the mean caffeine sensitivity was found between type I masseter fibers [2.57 +/- 1.32 (SD) mM] vs. type I (6.02 +/- 1.74 mM) and type II vastus lateralis fibers (11.25 +/- 3.13 mM). Maximal Ca(2+)-activated force per cross-sectional area was significantly different between masseter and vastus lateralis fibers. However, the Ca2+ concentration corresponding to half-maximal tension (pCa50) was not significantly different between type I masseter (pCa50 5.9 +/- 0.02) and type I vastus lateralis muscle (pCa50 6.01 +/- 0.08). These results suggest that the increase in caffeine sensitivity of masseter muscle reflects the presence of a low reactivity threshold of the sarcoplasmic reticulum.

scholarly journals Velocity, force, power, and Ca2+ sensitivity of fast and slow monkey skeletal muscle fibers

1998 ◽  
Vol 84 (5) ◽  
pp. 1776-1787 ◽  
Author(s):  
Robert H. Fitts ◽  
Sue C. Bodine ◽  
Janell G. Romatowski ◽  
Jeffrey J. Widrick
Keyword(s):  
Peak Power ◽  
Fiber Type ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Shortening Velocity ◽  
Hybrid Fibers ◽  
Slow Type ◽  
Type Ii Fibers

In this study, we determined the contractile properties of single chemically skinned fibers prepared from the medial gastrocnemius (MG) and soleus (Sol) muscles of adult male rhesus monkeys and assessed the effects of the spaceflight living facility known as the experiment support primate facility (ESOP). Muscle biopsies were obtained 4 wk before and immediately after an 18-day ESOP sit, and fiber type was determined by immunohistochemical techniques. The MG slow type I fiber was significantly smaller than the MG type II, Sol type I, and Sol type II fibers. The ESOP sit caused a significant reduction in the diameter of type I and type I/II (hybrid) fibers of Sol and MG type II and hybrid fibers but no shift in fiber type distribution. Single-fiber peak force (mN and kN/m2) was similar between fiber types and was not significantly different from values previously reported for other species. The ESOP sit significantly reduced the force (mN) of Sol type I and MG type II fibers. This decline was entirely explained by the atrophy of these fiber types because the force per cross-sectional area (kN/m2) was not altered. Peak power of Sol and MG fast type II fiber was 5 and 8.5 times that of slow type I fiber, respectively. The ESOP sit reduced peak power by 25 and 18% in Sol type I and MG type II fibers, respectively, and, for the former fiber type, shifted the force-pCa relationship to the right, increasing the Ca2+ activation threshold and the free Ca2+concentration, eliciting half-maximal activation. The ESOP sit had no effect on the maximal shortening velocity ( V o) of any fiber type. V o of the hybrid fibers was only slightly higher than that of slow type I fibers. This result supports the hypothesis that in hybrid fibers the slow myosin heavy chain would be expected to have a disproportionately greater influence on V o.

Do skeletal muscle phenotypic characteristics of Xhosa and Caucasian endurance runners differ when matched for training and racing distances?

2007 ◽  
Vol 103 (3) ◽  
pp. 932-940 ◽  
Author(s):  
Tertius A. Kohn ◽  
Birgitta Essén-Gustavsson ◽  
Kathryn H. Myburgh
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Dry Weight ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Endurance Running ◽  
Exercise Tests ◽  
Black And White ◽  
Endurance Runners

Although East African black athletes dominate endurance running events, it is unknown whether black and white endurance runners with similar racing ability, matched for training, may differ in their skeletal muscle biochemical phenotype. Thirteen Xhosa (XR) and 13 Caucasian (CR) endurance runners were recruited and matched for 10-km performance, average preferred racing distance (PRDA), and training volume. Submaximal and maximal exercise tests were done, and vastus lateralis muscle biopsies were taken. XR were significantly lighter and shorter than CR athletes but had similar maximum oxygen consumption corrected for body weight and peak treadmill speed (PTS). XR had lower plasma lactate concentrations at 80% PTS ( P < 0.05) compared with CR. Also, XR had more type IIA (42.4 ± 9.2 vs. 31.3 ± 11.5%, P < 0.05) and less type I fibers (47.8 ± 10.9 vs. 63.1 ± 13.2%, P < 0.05), although oxidative enzyme activities did not differ. Furthermore, XR compared with CR had higher lactate dehydrogenase (LDH) activity in homogenate muscle samples (383 ± 99 vs. 229 ± 85 μmol·min−1·g dry weight−1, P < 0.05) and in both type IIa ( P < 0.05) and type I ( P = 0.05) single-fiber pools. A marked difference ( P < 0.05) in the composition of LDH isoform content was found between the two groups with XR having higher levels of LDH5-4 isoforms (skeletal muscle isozymes; LDH-M) than CR, which was not accounted for by fiber-type differences alone. These results confirm differences in muscle phenotype and physiological characteristics, particularly associated with high-intensity running.

scholarly journals Histochemical, biochemical, and ultrastructural analyses of single human muscle fibers, with special reference to the C-fiber population.

1992 ◽  
Vol 40 (4) ◽  
pp. 563-568 ◽  
Author(s):  
R S Staron ◽  
R S Hikida
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Oxidative Capacity ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Heavy Chains ◽  
C Fibers ◽  
C Fiber ◽  
Ph Range

A muscle biopsy from the vastus lateralis muscle of a strength-trained woman was found to contain an unusual fiber type composition and was analyzed by histochemical, biochemical, and ultrastructural techniques. Special attention was given to the C-fibers, which comprised over 15% of the total fiber number in the biopsy. The mATPase activity of the C-fibers remained stable to varying degrees over the pH range normally used for routine mATPase histochemistry. Although a continuum existed, the C-fibers were histochemically subdivided into three main fiber types: IC, IIC, and IIAC. The IC fibers were histochemically more similar to the Type I, the IIAC were more similar to the Type IIA, and the IIC were darkly stained throughout the pH range. Biochemical analysis revealed that all C-fibers coexpressed myosin heavy chains (MHC) I and IIa in variable ratios. The histochemical staining intensity correlated with the myosin heavy chain composition such that the Type IC fibers contained a greater ratio of MHCI/MHCIIa, the IIAC contained a greater ratio of MHCIIa/MHCI, and the Type IIC contained equal amounts of these two heavy chains. Ultrastructural data of the C-fiber population revealed an oxidative capacity between fiber Types I and IIA and suggested a range of mitochondrial volume percent from highest to lowest such that I greater than IC greater than IIC greater than IIA-C greater than IIA. Under physiological conditions, it appears that the IC fibers represent Type I fibers that additionally express some fast characteristics, whereas the Type IIAC are Type IIA fibers that additionally express some slow characteristics. Fibers expressing a 50:50 mixture of MHCI and MHCIIa (IIC fibers) were rarely found. It is not known whether C-fibers represent a distinct population between the fast- and slow-twitch fibers that is specifically adapted to a particular usage or whether they are transforming fibers in the process of going from fast to slow or slow to fast.

Operation Everest II: adaptations in human skeletal muscle

1989 ◽  
Vol 66 (5) ◽  
pp. 2454-2461 ◽  
Author(s):  
H. J. Green ◽  
J. R. Sutton ◽  
A. Cymerman ◽  
P. M. Young ◽  
C. S. Houston
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Succinic Dehydrogenase ◽  
High Energy ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Type Ii ◽  
Cross Sectional ◽  
Distribution Type

Adaptations in skeletal muscle in response to progressive hypobaria were investigated in eight male subjects [maximal O2 uptake = 51.2 +/- 3.0 (SE) ml.kg-1.min-1] over 40 days of progressive decompression to the stimulated altitude of the summit of Mt. Everest. Samples of the vastus lateralis muscle extracted before decompression (SL-1), at 380 and 282 Torr, and on return to sea level (SL-2) indicated that maximal activities of enzymes representative of the citric acid cycle, beta-oxidation, glycogenolysis, glycolysis, glucose phosphorylation, and high-energy phosphate transfer were unchanged (P greater than 0.05) at 380 and 282 Torr over initial SL-1 values. After exposure to 282 Torr, however, representing an additional period of approximately 7 days, reductions (P less than 0.05) were noted in succinic dehydrogenase (21%), citrate synthetase (37%), and hexokinase (53%) between SL-2 and 380 Torr. No changes were found in the other enzymes. Capillarization as measured by the number of capillaries per cross-sectional area (CC/FA) was increased (P less than 0.05) in both type I (0.94 +/- 0.8 vs. 1.16 +/- 0.05) and type II (0.84 +/- 0.07 vs. 1.05 +/- 0.08) fibers between SL-1 and SL-2. This increase was mediated by a reduction in fiber area. No changes were found in fiber-type distribution (type I vs. type II). These findings do not support the hypothesis, at least in humans, that, at the level of the muscle cell, extreme hypobaric hypoxia elicits adaptations directed toward maximizing oxidative function.

Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase α- and β-isoforms in human skeletal muscle

2015 ◽  
Vol 118 (6) ◽  
pp. 699-706 ◽  
Author(s):  
V. L. Wyckelsma ◽  
M. J. McKenna ◽  
F. R. Serpiello ◽  
C. R. Lamboley ◽  
R. J. Aughey ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Western Blotting ◽  
Human Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Single Fiber ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Functional Roles

The Na+-K+-ATPase (NKA) plays a key role in muscle excitability, but little is known in human skeletal muscle about fiber-type-specific differences in NKA isoform expression or adaptability. A vastus lateralis muscle biopsy was taken in 17 healthy young adults to contrast NKA isoform protein relative abundance between type I and IIa fibers. We further investigated muscle fiber-type-specific NKA adaptability in eight of these adults following 4-wk repeated-sprint exercise (RSE) training, comprising three sets of 5 × 4-s sprints, 3 days/wk. Single fibers were separated, and myosin heavy chain (I and IIa) and NKA (α1–3 and β1–3) isoform abundance were determined via Western blotting. All six NKA isoforms were expressed in both type I and IIa fibers. No differences between fiber types were found for α1-, α2-, α3-, β1-, or β3-isoform abundances. The NKA β2-isoform was 27% more abundant in type IIa than type I fibers ( P < 0.05), with no other fiber-type-specific trends evident. RSE training increased β1 in type IIa fibers (pretraining 0.70 ± 0.25, posttraining 0.84 ± 0.24 arbitrary units, 42%, P < 0.05). No training effects were found for other NKA isoforms. Thus human skeletal muscle expresses all six NKA isoforms and not in a fiber-type-specific manner; this points to their different functional roles in skeletal muscle cells. Detection of elevated NKA β1 after RSE training demonstrates the sensitivity of the single-fiber Western blotting technique for fiber-type-specific intervention effects.

Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise

2007 ◽  
Vol 102 (1) ◽  
pp. 183-188 ◽  
Author(s):  
K. De Bock ◽  
W. Derave ◽  
M. Ramaekers ◽  
E. A. Richter ◽  
P. Hespel
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Content ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Periodic Acid ◽  
Carbohydrate Intake ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Type I Fibers ◽  
Glycogen Sparing

The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers ( n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise (∼75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before (∼150 g) and during (1 g·kg body weight−1·h−1) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 ± 1 × 10−2 optical density (OD)/μm2] than in type I fibers (8.0 ± 1 × 10−2 OD/μm2; P < 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 ± 1 × 10−2 OD/μm2 to 4.5 ± 1 × 10−2 OD/μm2 ( P = 0.001), but it did not significantly change during CHO ( P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.

Influence of complete spinal cord injury on skeletal muscle within 6 mo of injury

1999 ◽  
Vol 86 (1) ◽  
pp. 350-358 ◽  
Author(s):  
Michael J. Castro ◽  
David F. Apple ◽  
Robert S. Staron ◽  
Gerson E. R. Campos ◽  
Gary A. Dudley
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cord Injury ◽  
Lateralis Muscle ◽  
Type I Fibers ◽  
Femoris Muscle ◽  
Over Time

This study examined the influence of spinal cord injury (SCI) on affected skeletal muscle. The right vastus lateralis muscle was biopsied in 12 patients as soon as they were clinically stable (average 6 wk after SCI), and 11 and 24 wk after injury. Samples were also taken from nine able-bodied controls at two time points 18 wk apart. Surface electrical stimulation (ES) was applied to the left quadriceps femoris muscle to assess fatigue at these same time intervals. Biopsies were analyzed for fiber type percent and cross-sectional area (CSA), fiber type-specific succinic dehydrogenase (SDH) and α-glycerophosphate dehydrogenase (GPDH) activities, and myosin heavy chain percent. Controls showed no change in any variable over time. Patients showed 27–56% atrophy ( P = 0.000) of type I, IIa, and IIax+IIx fibers from 6 to 24 wk after injury, resulting in fiber CSA approximately one-third that of controls. Their fiber type specific SDH and GPDH activities increased ( P ≤ 0.001) from 32 to 90% over the 18 wk, thereby approaching or surpassing control values. The relative CSA of type I fibers and percentage of myosin heavy chain type I did not change. There was apparent conversion among type II fiber subtypes; type IIa decreased and type IIax+IIx increased ( P ≤ 0.012). Force loss during ES did not change over time for either group but was greater ( P = 0.000) for SCI patients than for controls overall (27 vs. 9%). The results indicate that vastus lateralis muscle shows marked fiber atrophy, no change in the proportion of type I fibers, and a relative independence of metabolic enzyme levels from activation during the first 24 wk after clinically complete SCI. Over this time, quadriceps femoris muscle showed moderately greater force loss during ES in patients than in controls. It is suggested that the predominant response of mixed human skeletal muscle within 6 mo of SCI is loss of contractile protein. Therapeutic interventions could take advantage of this to increase muscle mass.

Acute effects of taurine on sarcoplasmic reticulum Ca2+ accumulation and contractility in human type I and type II skeletal muscle fibers

2014 ◽  
Vol 117 (7) ◽  
pp. 797-805 ◽  
Author(s):  
T. L. Dutka ◽  
C. R. Lamboley ◽  
R. M. Murphy ◽  
G. D. Lamb
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Muscle Fibers ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Contractile Apparatus ◽  
Type Ii Fibers

Taurine occurs in high concentrations in muscle and is implicated in numerous physiological processes, yet its effects on many aspects of contractility remain unclear. Using mechanically skinned segments of human vastus lateralis muscle fibers, we characterized the effects of taurine on sarcoplasmic reticulum (SR) Ca2+ accumulation and contractile apparatus properties in type I and type II fibers. Prolonged myoplasmic exposure (>10 min) to taurine substantially increased the rate of accumulation of Ca2+ by the SR in both fiber types, with no change in the maximum amount accumulated; no such effect was found with carnosine. SR Ca2+ accumulation was similar with 10 or 20 mM taurine, but was significantly slower at 5 mM taurine. Cytoplasmic taurine (20 mM) had no detectable effects on the responsiveness of the Ca2+ release channels in either fiber type. Taurine caused a small increase in Ca2+ sensitivity of the contractile apparatus in type I fibers, but type II fibers were unaffected; maximum Ca2+-activated force was unchanged in both cases. The effects of taurine on SR Ca2+ accumulation 1) only became apparent after prolonged cytoplasmic exposure, and 2) persisted for some minutes after complete removal of taurine from the cytoplasm, consistent with the hypothesis that the effects were due to an action of taurine from inside the SR. In summary, taurine potentiates the rate of SR Ca2+ uptake in both type I and type II human fibers, possibly via an action from within the SR lumen, with the degree of potentiation being significantly reduced at low physiological taurine levels.

Carbohydrate ingestion and single muscle fiber glycogen metabolism during prolonged running in men

1996 ◽  
Vol 81 (2) ◽  
pp. 801-809 ◽  
Author(s):  
O. K. Tsintzas ◽  
C. Williams ◽  
L. Boobis ◽  
P. Greenhaff
Keyword(s):  
Fiber Type ◽  
Vastus Lateralis ◽  
Time To Exhaustion ◽  
Endurance Capacity ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Glycogen Depletion ◽  
Carbohydrate Ingestion ◽  
Atp Production ◽  
Type I Fibers

The aim of this study was to examine the effect of carbohydrate (CHO) ingestion on glycogen degradation in type I and type II muscle fibers during prolonged running by using a quantitative biochemical method. To this end, eight male subjects ran at 70% maximal oxygen uptake to exhaustion on a motorized treadmill on two occasions, 1 wk apart. On each occasion, the subjects ingested 8 ml/kg body wt of either placebo (Pl) or a 5.5% CHO-electrolyte solution (CHO-E) immediately before the start of the run and 2 ml/kg body wt every 20 min thereafter. Needle biopsy samples were obtained from the vastus lateralis muscle before and after each trial and also at the time coinciding with Pl exhaustion in the CHO-E trial. Running time to exhaustion was longer (P < 0.01) in the CHO-E trial compared with the Pl trial (132.4 +/- 12.3 and 104.3 +/- 8.6 min, respectively). A 25% reduction in glycogen utilization in type I fibers only was observed in the CHO-E trial compared with the Pl trial (215.2 +/- 27.5 vs. 285.4 +/- 30.1 mmol/kg dry wt; P < 0.01). Furthermore, in the CHO-E trial, in contrast to the Pl trial, both muscle ATP and phosphocreatine concentrations were well maintained throughout exercise. Therefore, because in both the Pl and CHO-E trials the type I fibers were glycogen depleted at the point of exhaustion (31.6 +/- 10.3 and 28.1 +/- 7.1 mmol/kg dry wt, respectively), it is proposed that CHO ingestion improved endurance capacity by contributing to oxidative ATP production specifically in type I fibers and by doing so delayed the development of glycogen depletion in this fiber type.

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