The vestibular system plays an important role in controlling arterial pressure upon posture change (vestibulo-cardiovascular reflex), although this system is highly plastic, i.e., the sensitivity of the vestibulo-cardiovascular reflex is altered if subjects are exposed to a different gravitational environment. Thus, it is possible that the sensitivity of vestibulo-cardiovascular reflex is diminished after spaceflight, and then orthostatic hypotension is induced. To test this hypothesis, the role of the vestibulo-cardiovascular reflex in maintaining arterial pressure upon posture change is examined before and after spaceflight.Principal Investigator(s)
Space Environment Utilization Center, Japan Aerospace Exploration Agency, Tsukuba, , Japan
Japan Aerospace Exploration Agency (JAXA)Sponsoring Organization
Information PendingResearch Benefits
Information PendingISS Expedition Duration:
May 2012 - September 2014Expeditions Assigned
31/32,33/34,35/36,37/38,39/40Previous ISS Missions
The objectives of the research are to test the hypothesis that vestibular-mediated pressure response is impaired after spaceflight, then orthostatic hypotension occurs. To examine this, contribution of the vestibulo-cardiovascular reflex in controlling arterial pressure upon HUT is examined before and after spaceflight. For transient interruption of the vestibular-mediated pressure response, galvanic vestibular stimulation (GVS) is applied. The HUT is performed with and without GVS. The contribution of vestibulo-cardiovascular reflex to arterial pressure maintenance during HUT is estimated by comparing the arterial pressure responses between GVS-on and GVS-off conditions.
This experiment has the potential benefits to the promotion of space medicine as well as human space flight.Earth Applications
This experiment has the potential benefits to considering a prophylaxis and countermeasure of orthostatic hypotension in elderly subjects. Both spaceflight and elderly subjects whose daily activity is reduced, fluctuation of the vestibular input is low and both conditions are known to induce orthostatic hypotension. Thus, it is possible that the plastic alteration of the vestibulo-cardiovascular reflex is a relevant mechanism of orthostatic hypotension in these conditions.
10 subjects are required. To accomplish this experiment, subjects are required to complete all 3 conditions (GVS-off, Strong GVS-on, Weak GVS-on), and at least 3 times of HUTs each condition for the data accuracy.Operational Protocols