Head-down bed rest alters sympathetic and cardiovascular responses to mental stress

Atsunori Kamiya, Satoshi Iwase, Daisaku Michikami, Qi Fu, Tadaaki Mano

Research output: Contribution to journalArticlepeer-review

41 Scopus citations


Astronauts usually work under much mental stress. However, it is unclear how and whether or not an exposure to microgravity affects physiological response to mental stress in humans. To examine effects of microgravity on vasomotor sympathetic and peripheral vasodilator responses to mental stress, we performed 10 min of mental arithmetic (MA) before and after 14 days of 6°head-down bed rest (HDBR), a ground-based simulation of spaceflight. Total muscle sympathetic nerve activity (MSNA, measured by microneurography) slightly increased during MA before HDBR, and this increase was augmented after HDBR. Calf blood flow (measured by venous occlusion plethysmography) increased and calf vascular resistance (calculated by dividing mean blood pressure by calf blood flow) decreased during MA before HDBR, but these responses were abolished after HDBR. Increases in heart rate and mean blood pressure during MA were not different between before and after HDBR. These findings suggest that HDBR augmented vasomotor sympathoexcitation but attenuated vasodilatation in the calf muscle in response to mental stress.

Original languageEnglish (US)
Pages (from-to)R440-R447
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number2 48-2
StatePublished - Sep 20 2000


  • Blood flow
  • Microgravity
  • Muscle sympathetic nerve activity
  • Vascular resistance

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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