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Implantation of Combined Telemetric ECG and Blood Pressure Transmitters to Determine Spontaneous Baroreflex Sensitivity in Conscious Mice
Published on: February 14, 2021
Human vagal baroreflex mechanisms in space.
Dwain L Eckberg1, John R Halliwill, Larry A Beightol
1Department of Medicine, Hunter Holmes McGuire Department of Veterans Affairs Medical Center and Medical College of Virginia at Virginia Commonwealth University, Richmond, VA, USA. deckberg@ekholmen.com
The Journal of Physiology
|February 17, 2010
Summary
Spaceflight impairs the body's ability to regulate blood pressure and heart rate. Astronauts experience altered baroreflex function in space, affecting cardiovascular responses upon return to Earth.
Area of Science:
- Cardiovascular Physiology
- Space Medicine
- Human Physiology
Background:
- Astronauts often experience orthostatic hypotension and tachycardia upon returning to Earth.
- Simulated microgravity impairs vagal baroreceptor-cardiac reflex function.
- Actual microgravity's effect on vagal baroreflex gain is debated.
Purpose of the Study:
- To test the hypothesis that spaceflight does not impair human baroreflex mechanisms.
- To investigate the effects of spaceflight on baroreceptor-cardiac reflex function.
Main Methods:
- Studied 13 astronauts before, during, and after space shuttle missions.
- Utilized graded neck pressure and suction to elicit carotid baroreflex R-R interval responses.
- Analyzed changes in systolic pressure, R-R intervals, and vagal baroreflex gain.
Main Results:
- Baseline systolic pressures were higher in space; R-R intervals were lower.
- Baroreceptor-cardiac reflex relations were displaced downward in space.
- Vagal baroreflex gain decreased by 9% by flight day 8.
Conclusions:
- Spaceflight significantly increases arterial pressure and impairs vagal baroreflex function.
- Microgravity exposure augments sympathetic and diminishes vagal cardiovascular influences.
- Baroreflex mechanisms return to preflight levels within 7-10 days post-flight.
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