Effect of temperature on post-tetanic potentiation in human dorsiflexor muscles

2001 ◽  
Vol 79 (1) ◽  
pp. 49-58 ◽  
Author(s):  
E Roderich Gossen ◽  
Kerry Allingham ◽  
Digby G Sale
Keyword(s):  
Relaxation Time ◽  
Rise Time ◽  
Wave Amplitude ◽  
Test Period ◽  
Warm Water ◽  
Effect Of Temperature ◽  
Type I ◽  
M Wave ◽  
Exposure To Cold ◽  
Post Tetanic Potentiation

The effect of temperature on post-tetanic potentiation (PTP) has been examined in the muscles of small mammals but not in human skeletal muscle. We examined PTP in the ankle dorsiflexor muscles of 10 young men by evoking twitches before and after a 7-second tetanus at 100 Hz in a control (room air ~21°C) condition and after immersion of the lower leg in warm (45°C) and cold (10°C) water baths for 30 min. Exposure to cold decreased tetanus and pre-tetanus twitch peak torque, but increased rise time, half-relaxation time, and muscle action potential (M-wave) amplitude; exposure to warm water had little effect. PTP was smallest in cold exposure 5 s post-tetanus, but persisted throughout the 12 min test period, whereas PTP had subsided by 6 min post-tetanus in control and warm exposures. M-wave amplitude initially decreased after exposure to warm water, recovered, then decreased again by 11 min post-tetanus. In contrast, exposure to cold had no initial effect but did increase the M-wave amplitude during the last half of the 12 min test period, similar to that seen in the control. The greatest immediate decrease in rise time and half-relaxation time was observed in the control; however, by 12 min post-tetanus warm exposure showed the greatest increase in rise time and half-relaxation time above pre-tetanus values. The decrease in the unpotentiated twitch torque with cooling in human dorsiflexors is typical for muscles with a predominance of type I (slow) fibres. The effect of cold on PTP is similar to that seen previously in mammalian muscles with a predominance of type II (fast) fibres, although the underlying mechanism of the cooling effect appears to differ.Key words: contraction, muscle, twitch.

Predicting cold-water bleaching in corals: role of temperature, and potential integration of light exposure

2020 ◽  
Vol 642 ◽  
pp. 133-146
Author(s):  
PC González-Espinosa ◽  
SD Donner
Keyword(s):  
Coral Bleaching ◽  
Cold Water ◽  
Light Exposure ◽  
Light Attenuation ◽  
Florida Keys ◽  
Cold Temperature ◽  
Warm Water ◽  
Coral Tissue ◽  
Effect Of Temperature ◽  
Type I

Warm-water growth and survival of corals are constrained by a set of environmental conditions such as temperature, light, nutrient levels and salinity. Water temperatures of 1 to 2°C above the usual summer maximum can trigger a phenomenon known as coral bleaching, whereby disruption of the symbiosis between coral and dinoflagellate micro-algae, living within the coral tissue, reveals the white skeleton of coral. Anomalously cold water can also lead to coral bleaching but has been the subject of limited research. Although cold-water bleaching events are less common, they can produce similar impacts on coral reefs as warm-water events. In this study, we explored the effect of temperature and light on the likelihood of cold-water coral bleaching from 1998-2017 using available bleaching observations from the Eastern Tropical Pacific and the Florida Keys. Using satellite-derived sea surface temperature, photosynthetically available radiation and light attenuation data, cold temperature and light exposure metrics were developed and then tested against the bleaching observations using logistic regression. The results show that cold-water bleaching can be best predicted with an accumulated cold-temperature metric, i.e. ‘degree cooling weeks’, analogous to the heat stress metric ‘degree heating weeks’, with high accuracy (90%) and fewer Type I and Type II errors in comparison with other models. Although light, when also considered, improved prediction accuracy, we found that the most reliable framework for cold-water bleaching prediction may be based solely on cold-temperature exposure.

Posttetanic potentiation of human dorsiflexors

1997 ◽  
Vol 83 (6) ◽  
pp. 2131-2138 ◽  
Author(s):  
Deborah D. O’Leary ◽  
Karen Hope ◽  
Digby G. Sale
Keyword(s):  
Relaxation Time ◽  
Rise Time ◽  
Time Course ◽  
Compound Action Potential ◽  
Peak Torque ◽  
Posttetanic Potentiation ◽  
M Wave ◽  
Time To Peak ◽  
Before And After ◽  
Compound Action

O’Leary, Deborah D., Karen Hope, and Digby G. Sale.Posttetanic potentiation of human dorsiflexors. J. Appl. Physiol. 83(6): 2131–2138, 1997.—Twitch contractions of the ankle dorsiflexors were evoked before and after applied 7-s tetanic stimulation at 100 Hz in 20 young adults. Torque decreased 15% during the tetanus. At 5 s after tetanus, twitch peak torque had potentiated 45%. Potentiation declined to 28% after 1 min, rose slightly to 33% at 2 min, and declined slowly with potentiation still 25% after 5 min. There was large intersubject variation in the amount of potentiation (5–140%) and its persistence (5 to ≥20 min). The muscle compound action potential (M wave) did not change significantly (from pretetanic value) at 5 s after tetanus but increased sharply (26%) at 2 min and then subsided. Twitch half relaxation time (23%) decreased significantly more than twitch rise time (13%) 5 s after tetanus and recovered more slowly. Twitch rates of torque development (75%) and relaxation (71%) increased similarly 5 s after tetanus and were still elevated (∼25%) at 5 min. The extent of twitch torque potentiation was significantly inversely correlated with pretetanic twitch rise time ( r = −0.69), half relaxation time ( r = −0.61), and twitch-to-tetanus ratio ( r = −0.66). The data indicate that posttetanic potentiation has a greater effect on twitch half relaxation time than on time to peak torque and is more prominent in muscles with a short twitch time course and small twitch-to-tetanus ratio.

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

scholarly journals Short-term resistance training with instability reduces impairment in V wave and H reflex in individuals with Parkinson’s disease

2019 ◽  
Vol 127 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Carla Silva-Batista ◽  
Jumes Leopoldino de Oliveira Lira ◽  
Fabian J. David ◽  
Daniel M. Corcos ◽  
Eugenia Casella Tavares Mattos ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Resistance Training ◽  
Wave Amplitude ◽  
H Reflex ◽  
Plantar Flexors ◽  
Short Term ◽  
M Wave ◽  
Reflex Responses ◽  
V Wave

This study had two objectives: 1) to compare the effects of 3 wk of resistance training (RT) and resistance training with instability (RTI) on evoked reflex responses at rest and during maximal voluntary isometric contraction (MVIC) of individuals with Parkinson’s disease (PD) and 2) to determine the effectiveness of RT and RTI in moving values of evoked reflex responses of individuals with PD toward values of age-matched healthy control subjects (HCs) ( z-score analysis). Ten individuals in the RT group and 10 in the RTI group performed resistance exercises twice a week for 3 wk, but only the RTI group included unstable devices. The HC group ( n = 10) were assessed at pretest only. Evoked reflex responses at rest (H reflex and M wave) and during MVIC [supramaximal M-wave amplitude (Msup) and supramaximal V-wave amplitude (Vsup)] of the plantar flexors were assessed before and after the experimental protocol. From pretraining to posttraining, only RTI increased ratio of maximal H-reflex amplitude to maximal M-wave amplitude at rest (Hmax/Mmax), Msup, Vsup/Msup, and peak torque of the plantar flexors ( P < 0.05). At posttraining, RTI was more effective than RT in increasing resting Hmax and Vsup and in moving these values to those observed in HCs ( P < 0.05). We conclude that short-term RTI is more effective than short-term RT in modulating H-reflex excitability and in increasing efferent neural drive, approaching average values of HCs. Thus short-term RTI may cause positive changes at the spinal and supraspinal levels in individuals with PD. NEW & NOTEWORTHY Maximal H-reflex amplitude (Hmax) at rest and efferent neural drive [i.e., supramaximal V-wave amplitude (Vsup)] to skeletal muscles during maximal contraction are impaired in individuals with Parkinson’s disease. Short-term resistance training with instability was more effective than short-term resistance training alone in increasing Hmax and Vsup of individuals with Parkinson’s disease, reaching the average values of healthy control subjects.

Histochemical and physiological characteristics of the rat diaphragm

1985 ◽  
Vol 58 (4) ◽  
pp. 1085-1091 ◽  
Author(s):  
J. M. Metzger ◽  
K. B. Scheidt ◽  
R. H. Fitts
Keyword(s):  
Fiber Type ◽  
Contractile Properties ◽  
Effect Of Temperature ◽  
Type I ◽  
Force Frequency ◽  
Rat Diaphragm ◽  
Shortening Velocity ◽  
Type Distribution ◽  
Adult Rat ◽  
Fiber Type Distribution

The histochemical and contractile characteristics of the adult rat diaphragm were determined. Based on enzyme histochemistry, the rat diaphragm contained 40% type I, 27% type IIa, and 34% type IIb fibers. There were significantly more type I fibers in the ventral costal (VEN) compared with the crural (CRU) region of the muscle and a slightly higher percentage of type I's on the thoracic relative to the abdominal surface. The contractile properties and the effect of temperature (Q10) were similar in the VEN and CRU regions. Increasing temperature produced higher isometric peak tetanic tension, whereas twitch tension, contraction, and one-half relaxation time all decreased. The maximal shortening velocity increased linearly from 22 and 30 degrees C, then plateaued before decreasing between 35 and 37 degrees C. The VEN and CRU force-velocity curves became less concave as temperature increased from 22 to 35 degrees C. Furthermore, the force-frequency relation of both regions was shifted to the right as temperature increased. The isometric and isotonic contractile properties and fiber type distribution are similar in the VEN and CRU regions of the diaphragm. The rat diaphragm is clearly heterogeneous in fiber type distribution and functionally lies intermediate between slow- and fast-twitch limb skeletal muscles.

The effect of bundle of warmth care for patients with advanced colorectal cancer undergoing chemotherapy on reduction of oxaliplatin-related peripheral sensory neuropathy.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e15031-e15031
Author(s):  
Jin-Xiang Lin ◽  
Zhan-hong Chen ◽  
Xiang-Wei Chen ◽  
Zu-Yan Fan ◽  
Xiu-Yan Huang ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Advanced Colorectal Cancer ◽  
Intervention Group ◽  
Sensory Neuropathy ◽  
Warm Water ◽  
Control Group ◽  
Peripheral Sensory Neuropathy ◽  
Exposure To Cold ◽  
Hands And Feet ◽  
Peripheral Sensory

e15031 Background: FOLFOX is the one of the most selected chemotherapy regimens for advanced colorectal carcinoma (aCC) patients, which includes oxaliplatin, 5-fu and leucovorin. However, oxaliplatin often causes chemotherapy-induced peripheral sensory neuropathy (CIPN) which is a common treatment-related adverse effect and affects long- term quality of life. The aim of the study is to observe the effect of warmth intervention on patients with advanced colorectal cancer undergoing chemotherapy. Methods: A total of 60 aCC patients were recruited. They were randomized into an intervention group (30 patients) and a control group (30 patients). The intervention group accepted the bundle of warmth care which included wearing cotton gloves and socks, washing hands and taking a bath with warm water, soaking hands and feet before sleep with warm water, reducing exposure to cold and avoiding cold food. The control group was treated with conventional health education which including how to reduce exposure to cold. CTCAE-4.0 was used to evaluate patient, s peripheral sensory neuropathy at baseline, 3 months, 6 months and 6 months after chemotherapy terminate. Results: At baseline, there was no peripheral sensory neuropathy in two groups. In 3 months, incidence of peripheral sensory neuropathy of intervention group and control group were 26.67%(Ⅰ:20.00%,Ⅱ:6.67%) VS 83.34% (Ⅰ:46.67%,Ⅱ:30.00%,Ⅲ:6.67%)(χ2= 22.289,p = 0.000). In 6 months, incidence of peripheral sensory neuropathy of two group were 36.67% (Ⅰ: 26.67%,Ⅱ: 10.00%) VS 93.34%(Ⅰ:46.67%,Ⅱ:30.00%,Ⅲ:16.67%) (χ2= 23.398,p = 0.000). 6 months after chemotherapy terminate, incidence of peripheral sensory nerve damage of two group were 13.33%(Ⅰ:10.00%,Ⅱ:3.33%) VS 33.34%(Ⅰ:6.67%,Ⅱ:10.00%,Ⅲ:6.67%) (χ2= 4.283,p = 0.233). Conclusions: Bundle of warmth care reduced oxaliplatin-related peripheral sensory neuropathy on patients with advanced colorectal cancer undergoing chemotherapy.

Fatigability, relaxation properties, and electromyographic responses of the human paralyzed soleus muscle

1995 ◽  
Vol 73 (6) ◽  
pp. 2195-2206 ◽  
Author(s):  
R. K. Shields
Keyword(s):  
Soleus Muscle ◽  
Wave Amplitude ◽  
Close Association ◽  
Muscle Relaxation ◽  
Peak Torque ◽  
M Wave ◽  
Relaxation Properties ◽  
Fatigue Protocol ◽  
Acute Group ◽  
Muscle Action Potential

1. The goal of this study was to characterize the fatigability, contractile relaxation properties, electrophysiological responses, and histochemical properties of the human paralyzed soleus muscle to determine its relative plasticity. 2. Acute (< 6 wk, n = 3) and chronic (> 1 yr, n = 10) paralyzed individuals had the tibial nerve activated with a 20-Hz square wave delivered for 330 ms every second for 4 min. The soleus muscle peak torque, one-half relaxation time (1/2RT), normalized maximum rate of relaxation (nMRR), and mass muscle action-potential amplitude (M wave) were computed every 30 s. A soleus muscle biopsy was evaluated for myosin adenosine triphosphatase enzyme (ATPase; pH 9.4, 4.6, and 4.2) and nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR). 3. In the chronically paralyzed group the torque was significantly reduced within 30 s of the fatigue protocol. The 1/2RT and nMRR were also significantly changed within 30 s, supporting that muscle relaxation was prolonged. No significant changes were present at comparable times during the same 4-min fatigue protocol applied to the acutely paralyzed soleus muscle. M-wave amplitude was significantly reduced in the chronic group, but only at 3 min of the fatigue protocol. Conversely, no significant changes occurred to the M waves of the acute group. 4. The correlation was high between torque and nMRR (r = 0.88-0.97) and torque and 1/2RT (r = 0.88-0.96) for each chronic subject. A close association was also found between 1/2RT and nMRR (r = 0.88-0.92) for each chronic subject. Because these variables changed minimally in the acutely paralyzed group, a lower correlation was present (r = 0.45-0.52). 5. Torque was weakly correlated to M-wave amplitude (r = 0.55) for the chronically paralyzed group. The greatest change in torque occurred at a time (0-65 s) when the least amount of change occurred in the M-wave amplitude, suggesting that the source of fatigue was within the contractile mechanism and not attributable to neuromuscular transmission compromise. 6. Despite a close association between torque and relaxation properties during fatigue of the chronically paralyzed soleus muscle, there was a significant dissociation after 5 min of recovery. Torque recovered to 60%, whereas the relaxation properties were consistently fully recovered. This suggests that the mechanism causing torque reduction covaried with the mechanism leading to prolonged relaxation during fatigue, but during recovery the two mechanisms no longer covaried. M-wave amplitude was also completely recovered at 5 min despite continued torque depression.(ABSTRACT TRUNCATED AT 400 WORDS)

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