scholarly journals Muscle fatigue examined at different temperatures in experiments on intact mammalian (rat) muscle fibers

2009 ◽  
Vol 106 (2) ◽  
pp. 378-384 ◽  
Author(s):  
H. Roots ◽  
G. Ball ◽  
J. Talbot-Ponsonby ◽  
M. King ◽  
K. McBeath ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Power Output ◽  
Force Depression ◽  
Output Force ◽  
Different Temperatures ◽  
Force Velocity ◽  
C 30 ◽  
C 50 ◽  
Shortening Contractions

In experiments on small bundles of intact fibers from a rat fast muscle, in vitro, we examined the decline in force in repeated tetanic contractions; the aim was to characterize the effect of shortening and of temperature on the initial phase of muscle fatigue. Short tetanic contractions were elicited at a control repetition rate of 1/60 s, and fatigue was induced by raising the rate to 1/5 s for 2–3 min, both in isometric mode (no shortening) and in shortening mode, in which each tetanic contraction included a ramp shortening at a standard velocity. In experiments at 20°C ( n = 12), the force decline during a fatigue run was 25% in the isometric mode but was significantly higher (35%) in the shortening mode. In experiments at different temperatures (10–30°C, n = 11), the tetanic frequency and duration were adjusted as appropriate, and for shortening mode, the velocity was adjusted for maximum power output. In isometric mode, fatigue of force was significantly less at 30°C (∼20%) than at 10°C (∼30%); the power output (force × velocity) was >10× higher at 30°C than at 10°C, and power decline during a fatigue run was less at 30°C (∼20–30%) than at 10°C (∼50%). The finding that the extent of fatigue is increased with shortening contractions and is lower at higher temperatures is consistent with the view that force depression by inorganic phosphate, which accumulates within fibers during activity, may be a primary cause of initial muscle fatigue.

Fatigue of mouse soleus muscle, using the work loop technique.

1997 ◽  
Vol 200 (22) ◽  
pp. 2907-2912 ◽  
Author(s):  
G N Askew ◽  
I S Young ◽  
J D Altringham
Keyword(s):  
Soleus Muscle ◽  
Power Output ◽  
Cycle Frequency ◽  
Reduction In Force ◽  
Negative Work ◽  
Loop Shape ◽  
Force Velocity ◽  
Positive Work ◽  
Work Loop

The function of many muscles requires that they perform work. Fatigue of mouse soleus muscle was studied in vitro by subjecting it to repeated work loop cycles. Fatigue resulted in a reduction in force, a slowing of relaxation and in changes in the force-velocity properties of the muscle (indicated by changes in work loop shape). These effects interacted to reduce the positive work and to increase the negative work performed by the muscle, producing a decline in net work. Power output was sustained for longer and more cumulative work was performed with decreasing cycle frequency. However, absolute power output was highest at 5 Hz (the cycle frequency for maximum power output) until power fell below 20% of peak power. As cycle frequency increased, slowing of relaxation had greater effects in reducing the positive work and increasing the negative work performed by the muscle, compared with lower cycle frequencies.

A study on the effect of new prepared amide cationic amphipathic on the corrosion inhibition of API N80 steel pipelines in oil wells industries

2018 ◽  
Vol 65 (2) ◽  
pp. 197-209 ◽  
Author(s):  
Samy Shaban ◽  
Abd Elaziz Fouda ◽  
Mohamed Elmorsi ◽  
Tarek Fayed ◽  
Omar Azazy
Keyword(s):  
Corrosion Inhibition ◽  
Density Functional ◽  
Electrochemical Impedance ◽  
Simple Method ◽  
Content Type ◽  
N80 Steel ◽  
Different Temperatures ◽  
Capacitive Loop ◽  
C 30 ◽  
C 50

Purpose The purpose of this study is to inspect the corrosion inhibition of API N80 steel pipelines in uninhibited solution and inhibited with a synthesized surfactant compound [N-(3-(dimethyl octyl ammonio) propyl) palmitamide bromide] (DMDPP), which is prepared through a simple and applicable method. Design/methodology/approach Weight loss was inspected at five different temperatures of 25°C, 30°C, 40°C, 50°C and 60°C Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation were used at room temperature. Density functional theory was used to study the relation between the molecular structure and inhibition theoretically. Findings Adsorption of the prepared DMDPP fits the Langmuir isotherm model. The inhibition efficiency of the prepared DMDPP amphipathic inhibitor is directly proportional to temperature increase. Polarization results reveal that the investigated DMDPP amphipathic compound behaves as a mixed-type inhibitor. EIS spectra produced one individual capacitive loop. Originality/value The originality is the preparation of cationic surfactants through a simple method, which can be used as corrosion inhibitors in oil production. The synthesized inhibitors were prepared from low-price materials. The work studied the behavior of the synthesized surfactants in inhibiting the corrosion of the steel in an acidic medium. Electrochemical and theoretical studies were presented, besides gravimetric and surface examination.

Cytochrome C suppresses renal accumulation and nephrotoxicity of polymyxin B

2018 ◽  
Vol 38 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Z-D Li ◽  
J Luo ◽  
L-H Jia ◽  
X-Y Wang ◽  
Z-K Xun ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Polymyxin B ◽  
Control Group ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
C 30 ◽  
C 50

The receptor megalin plays an important role in the accumulation of polymyxin B (PMB) in renal cells in vitro. This study aimed to examine the effects of cytochrome c (cyto c), a typical megalin ligand, on renal accumulation and nephrotoxicity of PMB in vivo. Thirty Sprague-Dawley rats were randomly divided into the vehicle control group, PMB group, PMB + cyto c 50, 100, or 200 mg/kg group, respectively, and were treated with intravenous cyto c 30 min before the administration of PMB 4.0 mg/kg once a day for consecutive 5 days. On the 4th day after administration, 24 h urine was collected to determine N-acetyl-β-D-glucosaminidase excretion. Six hours after the last injection on the 5th day, kidneys were harvested to assay PMB concentration and observe pathological alterations, and blood samples were collected to assay serum creatinine (SCr), blood urea nitrogen (BUN), and blood β2-microglobulin (β2-MG) levels. Cyto c 50, 100, and 200 mg/kg decreased the accumulation of PMB in the kidney by 18.5%, 39.1% ( p < 0.01), and 36.8% ( p < 0.01), respectively, and reduced 24 h N-acetyl-β-D- glucosaminidase excretion by 22.5% ( p < 0.05), 40.4% ( p < 0.01), and 40.4% ( p < 0.01), respectively. Kidney pathological damage induced by PMB was markedly reduced by cyto c 100 mg/kg and 200 mg/kg. However, there were no significant differences in SCr, BUN, and blood β2-MG levels among the groups. These results indicated that cyto c may inhibit the renal accumulation and nephrotoxicity of PMB in a rat model, further proving the role of megalin in the accumulation of PMB.

Shortening-induced depression of voluntary force in unfatigued and fatigued human adductor pollicis muscle

2003 ◽  
Vol 94 (1) ◽  
pp. 69-74 ◽  
Author(s):  
C. J. De Ruiter ◽  
A. De Haan
Keyword(s):  
Isometric Force ◽  
Experimental Studies ◽  
Adductor Pollicis ◽  
Voluntary Activation ◽  
Adductor Pollicis Muscle ◽  
Force Depression ◽  
Fatigued Muscle ◽  
Force Velocity ◽  
Shortening Contractions

The goals of this study were to investigate adductor pollicis muscle ( n = 7) force depression after maximal electrically stimulated and voluntarily activated isovelocity (19 and 306°/s) shortening contractions and the effects of fatigue. After shortening contractions, redeveloped isometric force was significantly ( P < 0.05) depressed relative to isometric force obtained without preceding shortening. For voluntarily and electrically stimulated contractions, relative force deficits respectively were (means ± SE) 25.0 ± 3.5 and 26.6 ± 1.9% (19°/s), 7.8 ± 2.2 and 11.5 ± 0.6% (306°/s), and 23.9 ± 4.4 and 31.6 ± 4.7% (19°/s fatigued). The relative force deficit was significantly smaller after fast compared with slow shortening contractions, whereas activation manner and fatigue did not significantly affect the deficit. It was concluded that in unfatigued and fatigued muscle the velocity-dependent relative force deficit was similar with maximal voluntary activation and electrical stimulation. These findings have important implications for experimental studies of force-velocity relationships. Moreover, if not accounted for in muscle models, they will contribute to differences observed between the predicted and the actually measured performance during in vivo locomotion.

MECHANISM OF PLASMINOGEN ACTIVATION AT LOW TEMPERATURE IN PLASMA SAMPLES CONTAINING THERAPEUTIC CONCENTRATIONS OF t-PA

1987 ◽  
Author(s):  
D C Rijken ◽  
E Seifried ◽  
M M Barrett-Bergshoeff ◽  
C Kluft
Keyword(s):  
Time Course ◽  
Tissue Type ◽  
Plasminogen Activation ◽  
Plasma Samples ◽  
Rapid Reduction ◽  
Different Temperatures ◽  
Long Time ◽  
In Vitro Effects ◽  
C 50

It is known that plasminogen activation in blood samples taken during thrombolytic therapy with tissue-type plasminogen activator (t-PA) may continue during plasma handling, leading to artificially low fibrinogen (Fbg) and α2-antiplasmin (AP) values. Addition of D-Phe-Pro-Arg-CH2Cl or quenching antibodies against t-PA prevents this phenomenon, but these additions do not allow measurement of t-PA activity. The question of this study is, why the in vitro effects occur, even during freezing of the samples. Normal plasma was supplemented with various amounts of two-chain melanoma or recombinant t-PA and stored at -20°C, with and without a prior snap-freeze procedure. AP consumption (chromo-genic substrate assay) and Fbg degradation (Clauss method), measured in thawed samples, were most pronounced in the non snap-frozen samples. As it took a relatively long time before these samples were really frozen, the time course of the effects was studied at different temperatures. Plasma samples containing 1000 IU t-PA per ml were incubated at 37, 25,10, 0 and -8°C between 0 and 120 min. AP reduction was most rapid at 37°C (50% after 13 min), was less at 25°C (50% after 30 min), but did not further decrease at lower temperatures. The AP reduction at temperatures between 25 and -8°C corresponded to the effect of 40% t-PA activity at 37°C. The Fbg values gave a similar picture: the most rapid reduction occurred at 37°C, a slower reduction at 25°C, but no further reduction (even a small increase) was found from 25 to -8°C. The experiments were repeated in a purified system, consisting of t-PA, plasminogen, Fbg and AP. In contrast to the plasma system, AP reduction gradually decreased from 37 to 0°C. The apparent t-PA activity at 0°C was 6% of the activity at 37 °C.It is concluded that the in vitro effects in plasma samples containing t-PA can be, at least partially, explained by an abnormally strong plasminogen activation around 0°C. A normal temperature dependency in the purified system strongly suggests that unknown plasma factors enhance plasminogen activation at low temperatures.

scholarly journals Effect of temperature, CO2 and O2 on motility and mobility of Anisakidae larvae

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aiyan Guan ◽  
Inge Van Damme ◽  
Frank Devlieghere ◽  
Sarah Gabriël
Keyword(s):  
Enzymatic Digestion ◽  
Infected Fish ◽  
Effect Of Temperature ◽  
Video Recordings ◽  
Different Temperatures ◽  
Semi Solid ◽  
Zoonotic Parasites ◽  
The Impact ◽  
Phosphate Buffered Saline

AbstractAnisakidae, marine nematodes, are underrecognized fish-borne zoonotic parasites. Studies on factors that could trigger parasites to actively migrate out of the fish are very limited. The objective of this study was to assess the impact of different environmental conditions (temperature, CO2 and O2) on larval motility (in situ movement) and mobility (migration) in vitro. Larvae were collected by candling or enzymatic digestion from infected fish, identified morphologically and confirmed molecularly. Individual larvae were transferred to a semi-solid Phosphate Buffered Saline agar, and subjected to different temperatures (6 ℃, 12 ℃, 22 ℃, 37 ℃) at air conditions. Moreover, different combinations of CO2 and O2 with N2 as filler were tested, at both 6 °C and 12 °C. Video recordings of larvae were translated into scores for larval motility and mobility. Results showed that temperature had significant influence on larval movements, with the highest motility and mobility observed at 22 ℃ for Anisakis spp. larvae and 37 ℃ for Pseudoterranova spp. larvae. During the first 10 min, the median migration of Anisakis spp. larvae was 10 cm at 22 ℃, and the median migration of Pseudoterranova spp. larvae was 3 cm at 37 ℃. Larval mobility was not significantly different under the different CO2 or O2 conditions at 6 °C and 12 ℃. It was concluded that temperature significantly facilitated larval movement with the optimum temperature being different for Anisakis spp. and Pseudoterranova spp., while CO2 and O2 did not on the short term. This should be further validated in parasite-infected/spiked fish fillets.

Injury to skeletal muscle fibers of mice following lengthening contractions

1985 ◽  
Vol 59 (1) ◽  
pp. 119-126 ◽  
Author(s):  
K. K. McCully ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscle ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Lengthening Contractions ◽  
Control Value ◽  
Skeletal Muscle Fibers ◽  
Maximum Isometric Force ◽  
Distal Tendon ◽  
Shortening Contractions

We tested the hypothesis that lengthening contractions result in greater injury to skeletal muscle fibers than isometric or shortening contractions. Mice were anesthetized with pentobarbital sodium and secured to a platform maintained at 37 degrees C. The distal tendon of the extensor digitorum longus muscle was attached to a servomotor. A protocol consisting of isometric, shortening, or lengthening contractions was performed. After the contraction protocol the distal tendon was reattached, incisions were closed, and the mice were allowed to recover. The muscles were removed after 1–30 days, and maximum isometric force (Po) was measured in vitro at 37 degrees C. Three days after isometric and shortening contractions and sham operations, histological appearance was not different from control and Po was 80% of the control value. Three days after lengthening contractions, histological sections showed that 37 +/- 4% of muscle fibers degenerated and Po was 22 +/- 3% of the control value. Muscle regeneration, first seen at 4 days, was nearly complete by 30 days, when Po was 84 +/- 3% of the control value. We conclude that, with the protocol used, lengthening, but not isometric or shortening contractions, caused significant injury to muscle fibers.

Power Output Force Generation by a MEMS Phase Change Actuator

2011 ◽  
Vol 20 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Leland W. Weiss ◽  
Cill D. Richards ◽  
Robert F. Richards
Keyword(s):  
Phase Change ◽  
Power Output ◽  
Force Generation ◽  
Output Force

Abstract TP35: Estimation of Red Blood Cells in the Thrombus Using MRI. A Phantom Study with Predetermined Thrombus Components

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Ana Paula Narata ◽  
Isabelle Filipiak ◽  
Richard Bibi ◽  
Jean Philippe Cottier ◽  
Kevin Janot
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Spin Echo ◽  
In Vitro Study ◽  
Fibrin Clot ◽  
Fluid Attenuated Inversion Recovery ◽  
Magnetic Resonance Imaging Mri ◽  
C 50 ◽  
D 20

Background and Purpose: Better understanding about thrombus composition seems necessary, as treatment of acute ischemic stroke (AIS) is focus on clot chemical dissolution and mechanical extraction. We propose to evaluate whether magnetic resonance imaging (MRI) can differentiate white from red clots and estimate red blood cells percentage (RBC%) using clots with predetermined components and an index based on MRI signal intensity (SI). Material and Methods: 5 clots (A=100% fibrin, B=80% RBC, C=50% RBC, D=20% RBC, E=unknown) were fixed in gelatin-manganese solution and studied by: high-resolution 3D T1-weighted (T1MPR), T2-weighted turbo spin echo (T2TSE), T2-weighted gradient echo (T2GE), susceptibility weighted (SWI), fluid-attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI) with apparent diffusion coefficient (ADC). SI index was calculated with clot SI and gelatin SI. Statistical analysis compared RBC-clots to fibrin-clot SI index and the correlation of RBC% and SI index in each MRI sequence. Results: Each red clot was different from clot A except clot D in FLAIR. Correlation between clots SI index and RBC concentration were found in T1MPR (r=-0.84), SWI (r=-0.79), T2GE (r=-0.72) and FLAIR (r=0.80). Linear regression resolution provided an indirect RBC estimation for clot E: 47.3 % in T1MPR, SWI 41.5%, T2GE 45.1% and FLAIR 50.9%. Histological analysis confirmed clot E composition. Conclusion: This in vitro study suggests that MRI can differentiate white from red clots except clots with low RBC% in FLAIR and also provide approximate RBC%.

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

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