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Experiment Overview


Information provided courtesy of the Japan Aerospace and Exploration Agency (JAXA).
Brief Summary

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)

Hironobu Morita, Ph.D., M. D., Gifu University Graduate School of Medicine, Japan

Co-Investigator(s)/Collaborator(s)

Yoshiharu Yamamoto, Ph.D, The University of Tokyo, Graduate School of Education, Bunkyo-ku, Tokyo , Japan

Kunihiko Tanaka, M.D., Ph.D., , Gifu University of Medical Science, Gifu, Japan

Chikara Abe, D.D.S., Ph.D., Gifu University Graduate School of Medicine, Seki , Japan

Developer(s)

Space Environment Utilization Center, Japan Aerospace Exploration Agency, Tsukuba, , Japan

Sponsoring Space Agency

Japan Aerospace Exploration Agency (JAXA)

Sponsoring Organization

Information Pending

Research Benefits

Information Pending

ISS Expedition Duration:

May 2012 - September 2014

Expeditions Assigned

31/32,33/34,35/36,37/38,39/40

Previous ISS Missions

Information Pending

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Experiment Description

Research Overview

• Orthostatic hypotension is one of the most common physical complications of spaceflight. One of the proposed mechanisms of this condition is the plastic alteration of the vestibulo-cardiovascular reflex, i.e., microgravity induces a plastic alteration of this reflex that may result in inadequate adjustment of the arterial pressure upon posture change. This possibility has to be examined in order to consider a prophylaxis and countermeasure of postflight orthostatic hypotension.



• The purpose of the research is to test the hypothesis that microgravity induces plastic alteration of the vestibulo-cardiovascular reflex, and vestibular-mediated pressor response is impaired after spaceflight, then orthostatic hypotension occurs. To examine this, contribution of the vestibulo-cardiovascular reflex in controlling AP upon head-up tilt (HUT) is examined before and after spaceflight.



• The vestibular system is known to be highly plastic; there are direct evidences of the altered vestibulo-ocular and vestibulo-spinal reflexes after spaceflight. However, a direct evidence of the altered vestibulo-cardiovascular reflex after spaceflight does not exist.

Description

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.

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Applications

Space Applications

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.

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Operations

Operational Requirements

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

Information Pending

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Results/More Information

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Related Websites

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Imagery