Changes in muscle sympathetic nerve activity and effect of breathing maneuvers during microgravity induced by parabolic flight in humans.

S. Iwase, T. Mano, Jian Cui, H. Kitazawa, A. Kamiya, S. Miyazaki, Y. Sugiyama, C. Mukai, M. Kohno, S. Nagaoka

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

This study aimed to clarify how muscle sympathetic nerve activity (MSNA) in humans, which plays an important role in blood pressure control against gravity, is altered under microgravity (microG) conditions, and how the MSNA change is modified by breathing maneuvers. Ten subjects seated themselves in a jet aircraft with their knees extended. MSNA was recorded microneurographically from the left tibial nerve with simultaneous monitoring of ECG, blood pressure, respiration, and intrathoracic blood volume estimated by the impedance method during parabolic flight in a jet aircraft. In half of the parabolas, their respiration was controlled at 0.25 Hz by a metronome. Results: MSNA was enhanced under hypergravity just before microG entry, and immediately suppressed by microG induced by parabolic flight. The suppression was more marked with controlled than with uncontrolled respiration (51.6 +/- 7.2 vs 82.8 +/- 2.5%, mean +/- SE, 1G=100%). MSNA changes during microG correlated significantly to changes in blood pressure and intrathoracic blood volume. The blood pressure fall 10 to 15 sec after microG entry was less prominent with controlled than with uncontrolled respiration. We conclude that changes in arterial blood pressure and intrathoracic blood volume modulate MSNA during microG induced by parabolic flight, depending largely on breathing maneuvers.

Original languageEnglish (US)
Pages (from-to)152-155
Number of pages4
JournalEnvironmental medicine : annual report of the Research Institute of Environmental Medicine, Nagoya University
Volume42
Issue number2
StatePublished - Jan 1 1998

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)

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