Artificial gravity: a possible countermeasure for post-flight orthostatic intolerance

Area of Science:

• Space medicine
• Human physiology
• Neuroscience

Background:

• Spaceflight causes deconditioning of the otolith-ocular reflex and orthostatic intolerance.
• Previous studies indicate a decline in these functions after space missions.

Purpose of the Study:

• To investigate the effects of artificial gravity via centrifugation on otolith-ocular reflexes and orthostatic responses in astronauts.
• To determine if artificial gravity could serve as a countermeasure to spaceflight-induced deconditioning.

Main Methods:

• Four astronauts experienced sustained linear acceleration in a centrifuge during the Neurolab (STS-90) mission.
• Otolith-ocular reflexes were assessed during and after flight.
• Orthostatic intolerance was evaluated using head-up passive tilt post-flight.
• A comparison was made with two crewmembers not exposed to artificial gravity.

Main Results:

• Otolith-ocular reflexes remained preserved in centrifuged astronauts, unlike in previous studies.
• No centrifuged astronauts exhibited orthostatic intolerance post-flight.
• One non-centrifuged astronaut showed orthostatic intolerance, supporting the hypothesis.

Conclusions:

• In-flight artificial gravity may counteract the deconditioning of otolith-ocular reflexes.
• Centrifugation might preserve hemodynamic responses to orthostasis by maintaining the otolith-sympathetic reflex gain.
• Short-radius centrifugation shows promise as a countermeasure for post-spaceflight orthostatic intolerance.