Cerebral Blood Flow and PETCO2 on Neuromuscular Function During Environmental Stress
The Influence of Cerebral Blood Flow and Alkalosis on Neuromuscular Function During Environmental Stress
Environmental stress, such as low oxygen availability (hypoxia), has been associated with impaired neuromuscular performance; however, the mechanisms associated with these performance decrements remain unclear. While the majority of research suggests that the observed fatigue is related to the central nervous system, the influence of changes in cerebral blood flow (CBF) and associated changes in cerebral pH (partial pressure of carbon dioxide; PCO2) remains unexamined. In response to hypoxic stress, humans hyperventilate to maintain oxygen consumption, resulting in a hypocapnia mediated decrease in CBF and cerebral alkalosis (decreased PCO2). Previous research suggests that hyperventilation induces changes in neural excitability and synaptic transmission; however, it remains unclear if these changes are related to hypocapnia mediated decrease in CBF or cerebral alkalosis or both.
The purpose of the proposed research program is to examine the influence of changes in CBF and cerebral alkalosis on neuromuscular function during environmental stress. The research program will consist of 2 separate projects, summarized below in a table outlining the proposed protocols and resultant physiological manipulations. During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.
The research program will consist of 2 separate projects. Project 1 will examine the changes in CBF and alkalosis by using (a) indomethacin (decrease CBF; no change PCO2) and (b) hypocapnia (decrease CBF; decrease PCO2). Using a similar experimental design, Project 2 will examine the change in CBF and alkalosis during hypoxia by using (a) poikilocapnic hypoxia (decrease PO2; decrease CBF; decrease PCO2), (b) isocapnic hypoxia (decrease PO2; no change CBF; no change PCO2) and (c) isocapnic hypoxia + indomethacin (decrease PO2; decrease CBF; no change PCO2). During each manipulation, neuromuscular function will be evaluated and compared to baseline (normoxic) conditions using a repeated measures design.
Therefore, Project 1 will examine the separate and combined effect of changes in CBF and cerebral alkalosis on neuromuscular function independent of environmental manipulations. Subsequently, Project 2 will examine neuromuscular function during hypoxia while controlling CBF and cerebral alkalosis. It is hypothesized that changes in PCO2 and therefore, changes in cerebral alkalosis will contribute to neuromuscular fatigue independent of changes in CBF and oxygen availability.
研究概览
研究类型
注册 (实际的)
阶段
- 第四阶段
联系人和位置
学习地点
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Ontario
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St Catharines、Ontario、加拿大、L2S 3A1
- Brock University
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参与标准
资格标准
适合学习的年龄
接受健康志愿者
有资格学习的性别
描述
Inclusion Criteria:
- 18 to 25 yrs old; healthy males
Exclusion Criteria:
- diagnosed medical condition; NSAID allergy; smoker; high altitude exposure; implants
学习计划
研究是如何设计的？
设计细节
- 主要用途：基础科学
- 分配：随机化
- 介入模型：单组作业
- 屏蔽：单身的
武器和干预
参与者组/臂 |
干预/治疗 |
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实验性的：Drug
Indomethacin 1.2 mg kg 1 dose
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安慰剂比较：Placebo
flour capsule
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研究衡量的是什么？
主要结果指标
结果测量 |
措施说明 |
大体时间 |
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静息运动阈值
大体时间：从基线 90 分钟开始的变化
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在对运动皮层进行经颅磁刺激后，从肌肉中记录运动诱发电位。
静息运动阈值定义为引发运动诱发电位所需的最小刺激强度。
静息电机阈值将以毫伏为单位进行量化。
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从基线 90 分钟开始的变化
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最大自主收缩
大体时间：从基线 90 分钟开始的变化
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在最大自主收缩 (MVC) 测试期间，参与者的右臂将固定在一个定制的设备中，该设备用于隔离前臂屈曲并测量桡侧腕屈肌产生的力。
参与者将被要求制作一个 5 秒的 MVC，并被口头鼓励在整个收缩期间保持最大力量的产生。
MVC 将被量化为以牛顿米为单位的最大力产生。
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从基线 90 分钟开始的变化
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H-Reflex Amplitude
大体时间：Change from baseline 90-minutes
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The H-Reflex is an indirect measure of motor neuron excitability.
Initially, a maximal M-wave (M-max) will be elicited by stimulating (1 ms in duration; 15 s between stimuli) the median nerve incrementally (2 V increments) until the largest waveform is observed.
The peak-to-peak amplitude of this waveform is considered M-max.
Using similar procedures as above, a sub-maximal M-wave of 5% M-max will be elicited and the amplitude of the resultant H-reflex (a small waveform observed following the submaximal M-wave) will be calculated.
The amplitude of the H-reflex will be quantified in milllivolts.
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Change from baseline 90-minutes
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H-reflex latency
大体时间：Change from baseline 90-minutes
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The H-Reflex is an indirect measure of motor neuron excitability.
Initially, a maximal M-wave (M-max) will be elicited by stimulating (1 ms in duration; 15 s between stimuli) the median nerve incrementally (2 V increments) until the largest waveform is observed.
The peak-to-peak amplitude of this waveform is considered M-max.
Using similar procedures as above, a sub-maximal M-wave of 5% M-max will be elicited and the amplitude of the resultant H-reflex (a small waveform observed following the submaximal M-wave) will be calculated.
The onset latency of the H-reflex will be quantified in milliseconds.
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Change from baseline 90-minutes
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Voluntary Activation
大体时间：Change from baseline 90-minutes
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The level of neural drive to muscle during contraction is termed voluntary activation and will be estimated by interpolation of a single supramaximal motor evoked potential during the 5-second MVC contraction.
If extra force is evoked by the 'superimposed' stimulus then either the stimulated axons were not all recruited voluntarily or they were discharging at sub-tetanic rates.
Therefore, voluntary activation will be quantified as the amplitude of maximal voluntary force production, relative to the amplitude of the supramaximal MEP.
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Change from baseline 90-minutes
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次要结果测量
结果测量 |
措施说明 |
大体时间 |
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大脑中动脉血流速度
大体时间：从基线 90 分钟开始的变化
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大脑中动脉 (MCA) 血流速度将通过 2 MHz 经颅多普勒 (TCD) 超声探头进行无创测量，双侧连接到舒适的头带上，并固定在颧弓、耳廓延髓的前面。
多普勒探头将在时间窗口（靠近耳朵）上起搏，并将在整个实验协议期间保持原位。
MCA 速度将以厘米/秒为单位进行量化。
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从基线 90 分钟开始的变化
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Brachial Artery Blood flow
大体时间：Change from baseline 90-minutes
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Brachial artery blood flow will be measured non-invasively using a high-resolution ultrasound machine.
Participants will lie supine with their forearm extended in a comfortable position.
Blood flow measurements will be taken in the top 1/3 of the upper arm over the duration of 10 cardiac cycles (approximately 60 seconds).
Blood flow will be quantified in L/min.
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Change from baseline 90-minutes
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Internal Carotid Artery Blood Flow
大体时间：Change from baseline 90-minutes
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Internal carotid artery (ICA) blood flow will be measured non-invasively using a high-resolution ultrasound machine.
Participants will lie supine with a slight extension of the neck and at 45° of lateral flexion away from the side being scanned.
ICA measurements will be taken 1 cm superior to the common carotid bifurcation over the duration of 10 cardiac cycles (approximately 60 seconds).
Blood flow will be quantified in L/min.
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Change from baseline 90-minutes
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Blood pressure
大体时间：Change from baseline 90-minutes
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Beat by beat blood pressure will be calculated from the blood pressure waveform using finger photoplethysmography (Nexfin, bmeye), with a finger cuff placed directly over the middle finger on the left hand.
Blood pressure will be quantified in mmHg.
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Change from baseline 90-minutes
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Pulse oximetry
大体时间：Change from baseline 90-minutes
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A pulse oximetry probe will be placed over a finger to provide a continuous, non-invasive measurement of the blood oxygen saturation to confirm that the end-tidal forcing system is controlling oxygen delivery at the desired levels during each experiment.
Oxygen saturation will be quantified as a percentage.
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Change from baseline 90-minutes
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Heart Rate
大体时间：Change from baseline 90-minutes
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Heart rate will be measured by electrocardiogram.
Heart rate will be quantified in beats per minute.
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Change from baseline 90-minutes
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End-Tidal Gas Concentrations
大体时间：Change from baseline 90-minutes
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The end-tidal concentrations of oxygen and carbon dioxide will be measured and reported in mmHg.
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Change from baseline 90-minutes
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合作者和调查者
调查人员
- 首席研究员：Stephen Cheung, PhD、Brock University
研究记录日期
研究主要日期
学习开始
初级完成 (实际的)
研究完成 (实际的)
研究注册日期
首次提交
首先提交符合 QC 标准的
首次发布 (估计)
研究记录更新
最后更新发布 (实际的)
上次提交的符合 QC 标准的更新
最后验证
更多信息
此信息直接从 clinicaltrials.gov 网站检索，没有任何更改。如果您有任何更改、删除或更新研究详细信息的请求，请联系 register@clinicaltrials.gov. clinicaltrials.gov 上实施更改，我们的网站上也会自动更新.
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Mila (bMotion Technologies)完全的
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Universidad Autonoma de MadridCentro Universitario La Salle完全的