Ertl AC.
Circulation. 1998 Oct 27; 98: I471.
Vanderbilt Univ, Nashville, TN, USA.
Adaptation to microgravity (microG) leads to orthostatic intolerance (OI), similar to that seen in young, otherwise healthy patients with disabling idiopathic OI. The mechanism underlying OI after microG is not clear, but impaired sympathetic function has been thought to play a key role. To test this hypothesis, we measured for the first time, muscle sympathetic nerve activity (MSNA) at rest and in response to graded lower body negative pressure (LBNP) in three astronauts before and during spaceflight. Blood pressure was maintained during LBNP on earth (from 133 +/- 8/68 +/- 5 to 135 +/- l0/70 +/- 4 mm Hg at 0 and -30 mm Hg LBNP, respectively) and in space (from 146 +/- 6/77 +/- 1 to 152 +/- 7/77 +/- 2 mm Hg). In contrast, heart rate and MSNA responses to LBNP appear to be greater inflight compared to preflight [figure: see text]. Our results suggest that sympathetic and cardiovascular responses to orthostatic stress are preserved or augmented after adaptation to 2 weeks of space flight, consistent with the hypovolemia induced by microG. [table: see text]
Publication Types:
Keywords:
- Astronauts
- Blood Pressure
- Cardiovascular Physiology
- Food Handling
- Heart Rate
- Humans
- Hypovolemia
- Lower Body Negative Pressure
- Space Flight
- Stress
- Sympathetic Nervous System
- Weightlessness
- NASA Discipline Regulatory Physiology
- NASA Experiment Number 9301095
- Non-NASA Center
Other ID:
UI: 102184891
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