Sex Differences in Reflex Responses to Intermittent Hypoxia

Study Overview
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Brief Summary
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The purpose of the present study is to determine whether there are sex differences in the reflex responses to hypoxia in humans.

Detailed Description
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Over 35% of the US population will develop sleep apnea at some point in their life. Sleep apnea is the most common form of sleep disordered breathing and patients with sleep apnea are at increased risk of developing high blood pressure. Intermittent, repeated exposures to low oxygen during sleep (intermittent hypoxia, IH) has been implicated as the primary stimulus for increases in sympathetic nervous system activity and blood pressure with sleep apnea. Interestingly there are some reports of a lower incidence of hypertension in women with sleep apnea when compared to men. Results from the present study will provide information important to the investigator's understanding of potential sex-differences in clinical outcomes for conditions related to acute/chronic hypoxia and may have important implications for treatments which may improve blood pressure control in patients with sleep apnea.

Official Title
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Sex Differences in Reflex Responses to Intermittent Hypoxia

Conditions
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Healthy Participants

Intervention / Treatment
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* Other: Hypoxic exposure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy adult men and women; BMI <30 kg/m2; non-pregnant; non-breastfeeding; non-smokers; premenopausal women with a normal menstrual cycle unaffected by hormonal contraceptive use; taking no medications known to affect autonomic or cardiovascular function (PI discretion). Exclusion Criteria: taking any medications known to affect the cardiovascular or autonomic nervous system (e.g. alpha-blockers, beta-blockers, etc); a self-reported history of hepatic, renal, pulmonary, cardiovascular, or neurological diseases; stroke or neurovascular disease; bleeding/clotting disorder; sleep apnea or other sleep disorders; diabetes; smoking; history of alcoholism or substance abuse; hypertension.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Interventional Model Description: All participants will undergo same 30 minute intermittent hypoxia protocol.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Hypoxic Exposure<br>Men, and women in early or late follicular phase of menstrual cycle will be exposed to acute and intermittent hypoxic episodes. | Other: Hypoxic exposure<br>* 30 minutes of intermittent hypoxia<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline Hypoxic Ventilatory Response after intermittent hypoxia | Hypoxia breathing will be recorded before and after intermittent hypoxia | Through completion of intermittent hypoxia, an average of 3 hours | 
| Change from baseline Blood Pressure after intermittent hypoxia | Systolic and diastolic blood pressure will be recorded before and after intermittent hypoxia | Through completion of intermittent hypoxia, an average of 3 hours | 
| Change from baseline Forearm Blood Flow after intermittent hypoxia | Blood flow in the forearm will be recorded before and after intermittent hypoxia | Through completion of intermittent hypoxia, an average of 3 hours |