Vasodilation, Vasoconstriction
Conditions
Brief summary
The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes.
Detailed description
Each year, millions of people make journeys from low altitude regions to high altitude for recreation, travel, and religious pilgrimage. Carbon monoxide (CO) is commonly associated with cigarette smoke, exhaust fumes, and is viewed as a life-threatening toxic gas. Exposure to CO occurs during travel to and during activities common in high-altitude travel and pilgrimage including vehicle fumes, incense, and second-hand smoke exposure. High altitude exposure and CO exposure have been observed independently to have complex and opposing effects on vascular endothelial function. Observation of these stimuli together in a controlled environment may allow for further understanding of the underlying mechanisms of vascular physiology and adaptations to both high-altitude and CO exposure. The CarMA (Carbon Monoxide and Altitude) Study aims to observe the vascular effects of carbon monoxide exposure at low and high altitudes. Recently, other studies have showed a significant improvement in flow mediated dilation (FMD) with acute exposure to low levels of CO To date, no research has been presented concerning the effect of CO on vascular function at altitude. The present study aims to observe the effect of acute carbon monoxide exposure on 1) flow mediated dilation, 2) conduit artery flow in exercise induced reactive hyperemia at sea level and at altitude, and 3) the effect of CO on vascular function in a high altitude dwelling (sherpa) population.
Interventions
OTHERCarbon monoxide rebreathe
Carbon monoxide exposure to increase blood (Carboxyhemoglobin) COHb safely to \ 10%
DRUGSodium Nitroprusside
Bolus Sodium Nitroprusside (SNP) injection for endothelium-independent vasodilation measure
Bolus Phenylephrine injection for observe α1-mediated vasoconstriction during mild exercise
Sponsors
University of Alberta
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Masking description
Participant will not be aware of which rebreathe treatment (CO or Room Air) they are receiving.
Intervention model description
Participants will partake in both room air and CO exposure on 2 separate visits.
Eligibility
Sex/Gender
ALL
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
* Between the ages of 18-50 years * No medical history of cardiovascular, respiratory, nervous system, or metabolic disease. * Women must be pre-menopausal.
Exclusion criteria
* Participants with any known cardiovascular, respiratory, nervous system, or metabolic disease. * Having travelled above 2,000m within 1 month of testing at low and high altitude. * Women who are pregnant, confirmed by a pregnancy test. * Women who are post-menopausal. * Participants that are classified as obese (body mass index \> 30 kg/m2). * Participants who are current daily smokers. * Participants that are currently taking monoamine (MAO) inhibitors, or tricyclic antidepressants.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion | 15 minutes | Change in brachial artery diameter (assessed via ultrasound) following release of arterial occlusion |
| Blood flow within the brachial artery during rhythmic handgrip exercise. | 15 minutes | Blood flow within the brachial artery during rhythmic handgrip exercise. |
| Change in brachial artery conductance following an infusion of phenylephrine | 5 min | Change in brachial artery conductance following an infusion of phenylephrine |
Countries
Canada
Outcome results
None listed