A Study of the Contractility, Biochemistry and Morphology of an Isolated Preparation of Human Skeletal Muscle

1977 ◽  
Vol 52 (3) ◽  
pp. 291-297 ◽  
Author(s):  
R. F. W. Moulds ◽  
A. Young ◽  
D. A. Jones ◽  
R. H. T. Edwards
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Preceding Paper ◽  
High Energy ◽  
Contractile Properties ◽  
Morphological Examination ◽  
Surgical Biopsy ◽  
Fibre Type Composition ◽  
Type Composition

1. A new method of studying isolated human skeletal muscle has been evaluated. This involves the incubation and electrical stimulation of strips of muscle, obtained at surgical biopsy, that are tied at the cut ends of the fibre bundles. 2. Morphological examination showed that the fibres were sealed off at the cut ends. Damage appeared to be restricted to the areas immediately adjacent to the ties. 3. Contractile properties were well maintained for several hours and measurements of tissue metabolites showed that muscle contents of the high-energy phosphate compounds were well preserved. 4. The isolated preparations were found to have the same contractile properties as human quadriceps femoris studied in vivo by the methods described in the preceding paper. 5. Correlation was found between the relaxation speed of the isolated preparations and their fibre-type composition histochemically determined. 6. It is concluded that this technique is a valid addition to the present methods of studying the physiology and pharmacology of human skeletal muscle.

Effects of ischaemic training on force development and fibre-type composition in human skeletal muscle

1991 ◽  
Vol 11 (1) ◽  
pp. 41-49 ◽  
Author(s):  
O. Eiken ◽  
C. J. Sundberg ◽  
M. Esbjörnsson ◽  
A. Nygren ◽  
L. Kaijser
Keyword(s):  
Skeletal Muscle ◽  
Fibre Type ◽  
Human Skeletal Muscle ◽  
Fibre Type Composition ◽  
Force Development ◽  
Type Composition

scholarly journals Acute upregulation of PGC-1α mRNA correlates with training-induced increases in SDH activity in human skeletal muscle

2017 ◽  
Vol 42 (6) ◽  
pp. 656-666 ◽  
Author(s):  
Jacob T. Bonafiglia ◽  
Brittany A. Edgett ◽  
Brittany L. Baechler ◽  
Matthew W. Nelms ◽  
Craig A. Simpson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mrna Expression ◽  
Human Skeletal Muscle ◽  
Interval Training ◽  
Capillary Density ◽  
Oxidative Capacity ◽  
Peak Oxygen Uptake ◽  
Fibre Type Composition ◽  
Type Composition ◽  
Acute Responses

The purpose of the present study was to determine if acute responses in PGC-1α, VEGFA, SDHA, and GPD1–2 mRNA expression predict their associated chronic skeletal muscle molecular (SDH–GPD activity and substrate storage) and morphological (fibre-type composition and capillary density) adaptations following training. Skeletal muscle biopsies were collected from 14 recreationally active men (age: 22.0 ± 2.4 years) before (PRE) and 3 h after (3HR) the completion of an acute bout of sprint interval training (SIT) (eight 20-s intervals at ∼170% peak oxygen uptake work rate separated by 10 s of recovery). Participants then completed 6 weeks of SIT 4 times per week with additional biopsies after 2 (MID) and 6 (POST) weeks of training. Acute increases in PGC-1α mRNA strongly predicted increases in SDH activity (a marker of oxidative capacity) from PRE and MID to POST (PRE–POST: r = 0.81, r2 = 0.65, p < 0.01; MID–POST: r = 0.79, r2 = 0.62, p < 0.01) and glycogen content from MID to POST (r = 0.60, r2 = 0.36, p < 0.05). No other significant relationships were found between acute responses in PGC-1α, VEGFA, SDHA, and GPD1–2 mRNA expression and chronic adaptations to training. These results suggest that acute upregulation of PGC-1α mRNA relates to the magnitude of subsequent training-induced increases in oxidative capacity, but not other molecular and morphological chronic skeletal muscle adaptations. Additionally, acute mRNA responses in PGC-1α correlated with VEGFA, but not SDHA, suggesting a coordinated upregulation between PGC-1α and only some of its proposed targets in human skeletal muscle.

scholarly journals Efficiency of human skeletal muscle in vivo: comparison of isometric, concentric, and eccentric muscle action

1997 ◽  
Vol 83 (3) ◽  
pp. 867-874 ◽  
Author(s):  
T. W. Ryschon ◽  
M. D. Fowler ◽  
R. E. Wysong ◽  
A.-R. Anthony ◽  
R. S. Balaban
Keyword(s):  
Skeletal Muscle ◽  
Steady State ◽  
Production Rate ◽  
Human Skeletal Muscle ◽  
Atp Synthesis ◽  
High Energy ◽  
High Energy Phosphates ◽  
Muscle Action ◽  
Atp Production

Ryschon, T. W., Fowler, R. E. Wysong, A.-R. Anthony, and R. S. Balaban. Efficiency of human skeletal muscle in vivo: comparison of isometric, concentric, and eccentric muscle action. J. Appl. Physiol. 83(3): 867–874, 1997.—The purpose of this study was to estimate the efficiency of ATP utilization for concentric, eccentric, and isometric muscle action in the human tibialis anterior and extensor digitorum longus in vivo. A dynamometer was used to quantitate muscle work, or tension, while simultaneous 31P-nuclear magnetic resonance data were collected to monitor ATP, phosphocreatine, inorganic phosphate, and pH. The relative efficiency of the actions was estimated in two ways: steady-state effects on high-energy phosphates and a direct comparison of ATP synthesis rates with work. In the steady state, the cytosolic free energy dropped to the lowest value with concentric activity, followed by eccentric and isometric action for comparative muscle tensions. Estimates of ATP synthesis rates revealed a mechanochemical efficiency [i.e., ATP production rate/work (both in J/s)] of 15.0 ± 1.3% in concentric and 34.7 ± 6.1% in eccentric activity. The estimated maximum ATP production rate was highest in concentric action, suggesting an activation of energy metabolism under these conditions. By using direct measures of metabolic strain and ATP turnover, these data demonstrate a decreasing metabolic efficiency in human muscle action from isometric, to eccentric, to concentric action.

scholarly journals Expression of interleukin-15 in human skeletal muscle - effect of exercise and muscle fibre type composition

2007 ◽  
Vol 584 (1) ◽  
pp. 305-312 ◽  
Author(s):  
Anders Rinnov Nielsen ◽  
Remi Mounier ◽  
Peter Plomgaard ◽  
Ole Hartvig Mortensen ◽  
Milena Penkowa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibre ◽  
Fibre Type ◽  
Human Skeletal Muscle ◽  
Muscle Fibre Type ◽  
Fibre Type Composition ◽  
Type Composition ◽  
Interleukin 15

scholarly journals Intracellular energetics and critical Po2 in resting ischemic human skeletal muscle in vivo

2010 ◽  
Vol 299 (5) ◽  
pp. R1415-R1422 ◽  
Author(s):  
Ian R. Lanza ◽  
Michael A. Tevald ◽  
Douglas E. Befroy ◽  
Jane A. Kent-Braun
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Ex Vivo ◽  
High Energy ◽  
Resonance Spectroscopy ◽  
High Energy Phosphates ◽  
Atp Production ◽  
Resting Muscle

During ischemia and some types of muscular contractions, oxygen tension (Po2) declines to the point that mitochondrial ATP synthesis becomes limited by oxygen availability. Although this critical Po2 has been determined in animal tissue in vitro and in situ, there remains controversy concerning potential disparities between values measured in vivo and ex vivo. To address this issue, we used concurrent heteronuclear magnetic resonance spectroscopy (MRS) to determine the critical intracellular Po2 in resting human skeletal muscle in vivo. We interleaved measurements of deoxymyoglobin using 1H-MRS with measures of high-energy phosphates and pH using 31P-MRS, during 15 min of ischemia in the tibialis anterior muscles of 6 young men. ATP production and intramyocellular Po2 were quantified throughout ischemia. Critical Po2, determined as the Po2 corresponding to the point where PCr begins to decline (PCrip) in resting muscle during ischemia, was 0.35 ± 0.20 Torr, means ± SD. This in vivo value is consistent with reported values ex vivo and does not support the notion that critical Po2 in resting muscle is higher when measured in vivo. Furthermore, we observed a 4.5-fold range of critical Po2 values among the individuals studied. Regression analyses revealed that time to PCrip was associated with critical Po2 and the rate of myoglobin desaturation ( r = 0.83, P = 0.04) but not the rate of ATP consumption during ischemia. The apparent dissociation between ATP demand and myoglobin deoxygenation during ischemia suggests that some degree of uncoupling between intracellular energetics and oxygenation is a potentially important factor that influences critical Po2 in vivo.

Physical exercise increases autophagic signaling through ULK1 in human skeletal muscle

2015 ◽  
Vol 118 (8) ◽  
pp. 971-979 ◽  
Author(s):  
Andreas Buch Møller ◽  
Mikkel Holm Vendelbo ◽  
Britt Christensen ◽  
Berthil Forrest Clasen ◽  
Ann Mosegaard Bak ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Physical Exercise ◽  
Light Chain ◽  
Human Skeletal Muscle ◽  
Transgenic Animal ◽  
Dependent Manner ◽  
Healthy Humans ◽  
Transgenic Animal Models ◽  
Exercise Induced

Data from transgenic animal models suggest that exercise-induced autophagy is critical for adaptation to physical training, and that Unc-51 like kinase-1 (ULK1) serves as an important regulator of autophagy. Phosphorylation of ULK1 at Ser555 stimulates autophagy, whereas phosphorylation at Ser757 is inhibitory. To determine whether exercise regulates ULK1 phosphorylation in humans in vivo in a nutrient-dependent manner, we examined skeletal muscle biopsies from healthy humans after 1-h cycling exercise at 50% maximal O2 uptake on two occasions: 1) during a 36-h fast, and 2) during continuous glucose infusion at 0.2 kg/h. Physical exercise increased ULK1 phosphorylation at Ser555 and decreased lipidation of light chain 3B. ULK1 phosphorylation at Ser555 correlated positively with AMP-activated protein kinase-α Thr172 phosphorylation and negatively with light chain 3B lipidation. ULK1 phosphorylation at Ser757 was not affected by exercise. Fasting increased ULK1 and p62 protein expression, but did not affect exercise-induced ULK1 phosphorylation. These data demonstrate that autophagy signaling is activated in human skeletal muscle after 60 min of exercise, independently of nutritional status, and suggest that initiation of autophagy constitutes an important physiological response to exercise in humans.

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