Interaction of Otolith Stimulation and Carotid Baroreflex in Humans

Study Overview
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Brief Summary
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It is well documented that a few days stay in space induces a change in the vestibular-ocular reflex reflecting a reinterpretation of sensory inputs following the disappearance of gravity. If the change of eye reflexes actually the result of a reinterpretation of sensory input, the investigators should also expect to see an alteration of the vestibular-cardiovascular reflexes. The modification of these reflexes may modulate the carotid baroreflex and thus participate in the post-flight cardiovascular deconditioning. The first objective of this project is to study the carotid baroreflex under different supine (dorsal, ventral and lateral) inducing different otolith stimulation in normal-gravity.

Official Title
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Interaction of Otolith Stimulation and Carotid Baroreflex in Humans

Conditions
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Healthy Volunteers

Intervention / Treatment
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* Procedure: Stimulation of the carotid baroreceptors with a pressure system


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers, male and / or female aged 18-30 years subject affiliated to a social security scheme, agreeing to participate in the study and who provided informed consent. Exclusion Criteria: who participated in a clinical trial within less than the period of exclusion from this project with a past or present history of heart disease, vascular, neurological, respiratory, rheumatological, metabolic or otologic. pregnant women (dosage beta HCG) having taken any medication heart, vascular, neurological, respiratory, rheumatological, metabolic or might interfere on vestibular test results during the two years preceding the experiment. smoking or smoking more than 5 cigarettes / day, 1 cigarette / day or 1 pipe / day

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 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
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Carotid Baroreflex measurements<br> | Procedure: Stimulation of the carotid baroreceptors with a pressure system<br>* In each decubitus, trains of stimuli 8 (-80, -60, -40, -20, 0, 10, 20 and 40 Torr), with a duration of 500 milliseconds each, will be applied using a positive and negative pressure system placed around the neck of the subject.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Arterial flow in Common Carotid Artery (EchoDoppler) | Measurements of Common Carotid Artery Blood Flow in Cm/s | baseline | 
| Arterial flow in Internal Carotid Artery (EchoDoppler) | Measurements of Internal Carotid Artery Blood Flow in Cm/s | Baseline | 
| Arterial flow in External Carotid Artery (EchoDoppler) | Measurements of External Carotid Artery Blood Flow in Cm/s | Baseline | 
| Arterial flow in Vertebral Artery (EchoDoppler) | Measurements of Vertebral Artery Blood Flow in Cm/s | Baseline |