Effect of varied extracellular P O 2 on muscle performance inXenopus single skeletal muscle fibers

1999 ◽  
Vol 86 (6) ◽  
pp. 1812-1816 ◽  
Author(s):  
Creed M. Stary ◽  
Michael C. Hogan
Keyword(s):  
Skeletal Muscle ◽  
Mitochondrial Respiration ◽  
Muscle Fibers ◽  
Muscle Performance ◽  
Tetanic Force ◽  
Skeletal Muscle Fibers ◽  
Rate Limiting ◽  
Single Living ◽  
Initial Peak ◽  
Text Condition

The purpose of this study was to examine the development of fatigue in isolated, single skeletal muscle fibers when O2 availability was reduced but not to levels considered rate limiting to mitochondrial respiration. Tetanic force was measured in single living muscle fibers ( n = 6) from Xenopus laevis while being stimulated at increasing contraction rates (0.25, 0.33, 0.5, and 1 Hz) in a sequential manner, with each stimulation frequency lasting 2 min. Muscle fatigue (determined as 75% of initial maximum force) was measured during three separate work bouts (with 45 min of rest between) as the perfusate [Formula: see text] was switched between values of 30 ± 1.9, 76 ± 3.0, or 159 Torr in a blocked-order design. No significant differences were found in the initial peak tensions between the high-, intermediate-, and low-[Formula: see text] treatments (323 ± 22, 298 ± 27, and 331 ± 24 kPa, respectively). The time to fatigue was reached significantly sooner ( P < 0.05) during the 30-Torr treatment (233 ± 39 s) compared with the 76- (385 ± 62 s) or 159-Torr (416 ± 65 s) treatments. The calculated critical extracellular [Formula: see text]necessary to develop an anoxic core within these fibers was 13 ± 1 Torr, indicating that the extracellular[Formula: see text] of 30 Torr should not have been rate limiting to mitochondrial respiration. The magnitude of an unstirred layer (243 ± 64 μm) or an intracellular O2 diffusion coefficient (0.45 ± 0.04 × 10−5cm2/s) necessary to develop an anoxic core under the conditions of the study was unlikely. The earlier initiation of fatigue during the lowest extracellular[Formula: see text] condition, at physiologically high intracellular [Formula: see text] levels, suggests that muscle performance may be O2 dependent even when mitochondrial respiration is not necessarily compromised.

scholarly journals Impairment of Ca2+ release in single Xenopusmuscle fibers fatigued at varied extracellular P O 2

2000 ◽  
Vol 88 (5) ◽  
pp. 1743-1748 ◽  
Author(s):  
Creed M. Stary ◽  
Michael C. Hogan
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Rapid Onset ◽  
Skeletal Muscle Fibers ◽  
Significant Difference ◽  
Force Recovery ◽  
Series Of Experiments ◽  
Initial Peak ◽  
Time Point ◽  
Text Condition

We tested the hypothesis that the mechanisms involved in the more rapid onset of fatigue when O2 availability is reduced in contracting skeletal muscle are similar to those when O2 availability is more sufficient. Two series of experiments were performed in isolated, single skeletal muscle fibers from Xenopus laevis. First, relative force and free cytosolic Ca2+concentrations ([Ca2+]c) were measured simultaneously in single fibers ( n = 6) stimulated at increasing frequencies (0.25, 0.33, 0.5, and 1 Hz) at an extracellular[Formula: see text] of either 22 or 159 Torr. Muscle fatigue (force = 50% of initial peak tension) occurred significantly sooner ( P < 0.05) during the low- (237 ± 40 s) vs. high-[Formula: see text]treatments (280 ± 38 s). Relative [Ca2+]c was significantly decreased from maximal values at the fatigue time point during both the high- (72 ± 4%) and low-[Formula: see text] conditions (78 ± 4%), but no significant difference was observed between the treatments. In the second series of experiments, using the same stimulation regime as the first, fibers ( n = 6) exposed to 5 mM caffeine immediately after fatigue demonstrated an immediate but incomplete relative force recovery during both the low- (89 ± 4%) and high-[Formula: see text] treatments (82 ± 3%), with no significant difference between treatments. Additionally, there was no significant difference in relative [Ca2+]c between the high- (100 ± 12% of prefatigue values) and low-[Formula: see text] treatments (108 ± 12%) on application of caffeine. These results suggest that in isolated, single skeletal muscle fibers, the earlier onset of fatigue that occurred during the low-extracellular[Formula: see text] condition was modulated through similar pathways as the fatigue process during the high and involved a decrease in relative peak [Ca2+]c.

Cryopreservation with dimethyl sulfoxide prevents accurate analysis of skinned skeletal muscle fibers mitochondrial respiration

Biochimie ◽  
2014 ◽  
Vol 100 ◽  
pp. 227-233 ◽  
Author(s):  
Alain Meyer ◽  
Anne-Laure Charles ◽  
Joffrey Zoll ◽  
Max Guillot ◽  
Anne Lejay ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dimethyl Sulfoxide ◽  
Mitochondrial Respiration ◽  
Muscle Fibers ◽  
Accurate Analysis ◽  
Skeletal Muscle Fibers

scholarly journals Effects of high-intensity intermittent exercise on the contractile properties of human type I and type II skeletal muscle fibers

2020 ◽  
Vol 128 (5) ◽  
pp. 1207-1216 ◽  
Author(s):  
Cedric. R. Lamboley ◽  
David M. Rouffet ◽  
Travis L. Dutka ◽  
Michael J. McKenna ◽  
Graham D. Lamb
Keyword(s):  
Skeletal Muscle ◽  
High Intensity ◽  
Intermittent Exercise ◽  
Muscle Fibers ◽  
Muscle Performance ◽  
Type I ◽  
Type Ii ◽  
Contractile Apparatus ◽  
Skeletal Muscle Fibers ◽  
Type Ii Fibers

This study identified important cellular changes occurring in human skeletal muscle fibers following high-intensity intermittent exercise: 1) a decrease in contractile apparatus Ca2+ sensitivity in type I but not type II fibers, 2) a decrease in specific force only in type II muscle fibers, and 3) a redox-dependent increase in Ca2+ sensitivity occurring only in type II fibers, which would help maintain muscle performance by countering the normal metabolite-induced decline in Ca2+ sensitivity.

Effects of CO2-induced acidification on the fatigue resistance of single mouse muscle fibers at 28°C

1998 ◽  
Vol 85 (2) ◽  
pp. 478-483 ◽  
Author(s):  
Joseph D. Bruton ◽  
Jan Lännergren ◽  
Håkan Westerblad
Keyword(s):  
Skeletal Muscle ◽  
Intracellular Ph ◽  
Muscle Fibers ◽  
Initial Value ◽  
Mouse Muscle ◽  
Tetanic Force ◽  
Muscle Ph ◽  
Initial Peak ◽  
Stimulation Of

The role of reduced muscle pH in the development of skeletal muscle fatigue is unclear. This study investigated the effects of lowering skeletal muscle intracellular pH by exposure to 30% CO2 on the number of isometric tetani needed to induce significant fatigue. Isolated single mouse muscle fibers were stimulated repetitively at intervals of 4–2.5 s by using 80-Hz, 400-ms tetani at 28°C in Tyrode solution bubbled with either 5 or 30% CO2. Stimulation continued until tetanic force had fallen to 40% of the initial value. Exposure to 30% CO2 caused a significant fall in intracellular pH of ∼0.3 pH unit but did not cause any significant changes in initial peak tetanic force. During the course of repetitive stimulation, intracellular pH fell by ∼0.3 pH unit in both normal and acidified fibers. The number of tetani needed to reduce force to 40% of the initial value was not significantly different in 5 and 30% CO2Tyrode. The sole effect of acidosis was to reduce the rate of relaxation of force, especially in fatigued fibers. It is concluded that, at 28°C, acidosis per se does not accelerate the development of fatigue during repeated tetanic stimulation of isolated mouse skeletal muscle fibers.

The “KIMWIPE” Effect in Ultra-Thin Cryosections

1985 ◽  
Vol 43 ◽  
pp. 458-459
Author(s):  
I. Taylor ◽  
P. Ingram ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Fibers ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Thin Sections ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Ice Crystal Formation

In studying quick-frozen single intact skeletal muscle fibers for structural and microchemical alterations that occur milliseconds, and fractions thereof, after electrical stimulation, we have developed a method to compare, directly, ice crystal formation in freeze-substituted thin sections adjacent to all, and beneath the last, freeze-dried cryosections. We have observed images in the cryosections that to our knowledge have not been published heretofore (Figs.1-4). The main features are that isolated, sometimes large regions of the sections appear hazy and have much less contrast than adjacent regions. Sometimes within the hazy regions there are smaller areas that appear crinkled and have much more contrast. We have also observed that while the hazy areas remain still, the regions of higher contrast visibly contract in the beam, often causing tears in the sections that are clearly not caused by ice crystals (Fig.3, arrows).

Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

2019 ◽  
Author(s):  
Leonardo Hernández
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Free Calcium ◽  
Slow Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Chronic Denervation ◽  
Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

scholarly journals Development of a human neuromuscular tissue-on-a-chip model on a 24-well-plate-format compartmentalized microfluidic device

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Kazuki Yamamoto ◽  
Nao Yamaoka ◽  
Yu Imaizumi ◽  
Takunori Nagashima ◽  
Taiki Furutani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Microfluidic Device ◽  
Motor Neurons ◽  
Muscle Fibers ◽  
Three Dimensional ◽  
Tissue Model ◽  
Skeletal Muscle Fibers

A three-dimensional human neuromuscular tissue model that mimics the physically separated structures of motor neurons and skeletal muscle fibers is presented.

Sign in / Sign up

Export Citation Format

Share Document