Effect of Muscle Reflex Inhibition on Cardiorespiratory Responses to Exercise in Hypoxia
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 入组人数
- 14
- 试验地点
- 1
- 主要终点
- Ventilation
研究概览
简要总结
The goal of this interventional study is to compare muscle reflex function under settings of normoxia (normal oxygen level), acute hypoxia (brief oxygen-lack) and chronic hypoxia (long-duration exposure to oxygen-lack).
The main question is: Does the muscle reflex adapt to chronic hypoxia?
Young, healthy participants will complete light-to-high intensity cycling exercise with and without suppression of the muscle reflex. Suppression of the muscle reflex will be via spinal administration of the opioid Fentanyl. In the control condition, saline will be administered into the spinal space. Participants will complete control (saline) and experimental (Fentanyl) exercise conditions at sea-level (Kelowna, BC, Canada) breathing room air and whilst breathing a lower fraction of oxygen (acute hypoxia). Thereafter, participants will complete the exercise test after living at high altitude (White Mountain, CA, USA) for 2 weeks whilst breathing room air (chronic hypoxia) and breathing a higher fraction of oxygen (restored normoxia).
详细描述
Purpose:
To determine whether muscle reflex control of cardiorespiratory function is sensitized by chronic exposure to low oxygen environments. To do this, fentanyl will be administered into the lumbar spine to suppress nerve activity coming from the muscle during upright cycling exercise.
Hypothesis:
Cardiorespiratory responses (ventilation, blood pressure and heart rate) to cycling exercise will be suppressed when muscle reflex activity is partially blocked with fentanyl administration. This suppression will be augmented in a dose-dependent manner with the duration of hypoxic exposure.
Design:
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Basic Science
- 盲法
- Double (Participant, Investigator)
盲法说明
The participant will not know whether they are receiving placebo or fentanyl. The primary investigator will also no know if the participant is receiving placebo or fentanyl.
入排标准
- 年龄范围
- 19 Years 至 40 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •aged 19 - 40 years old
- •not taking medications (exception oral contraception)
- •no history of cardiovascular, respiratory or neurological disease
- •members of the high altitude expedition to White Mountain in 2023
排除标准
- •post-menopausal or pregnant
- •current smokers
- •taking prescription medications that may affect responses to exercise
- •All potential participants will be screened by a physician to identify co-morbidities
研究组 & 干预措施
Sea level control
Sea level exercise will be completed after the administration of 1 mL of isotonic saline into the intrathecal (spinal) space between L3-L4.
干预措施: Saline (Other)
Sea level experimental (muscle reflex suppression)
Sea level exercise will be completed after the administration of 0.25 mL of fentanyl into the intrathecal (spinal) space between L3-L4.
干预措施: Fentanyl (Drug)
High altitude control
High altitude exercise will be completed after the administration of 1 mL of isotonic saline into the intrathecal (spinal) space between L3-L4.
干预措施: Saline (Other)
High altitude experimental (muscle reflex suppression)
High altitude exercise will be completed after the administration of 0.25 mL of fentanyl into the intrathecal (spinal) space between L3-L4.
干预措施: Fentanyl (Drug)
结局指标
主要结局
Ventilation
时间窗: Data collected during steady-state breathing in the last minute of exercise
Ventilation, in liters per minute.
次要结局
- Mean arterial blood pressure (entire pressure wave)(Data collected during steady-state breathing in the last minute of exercise)
研究者
Phil Ainslie
Professor
University of British Columbia