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Central hemodynamics in a baboon model during microgravity induced by parabolic flight
R D Latham1, J W Fanton, M N Vernalis
1Laboratory for Aerospace Cardiovascular Research, Brooks Air Force Base, TX 78235-5301.
Advances in Space Research : the Official Journal of the Committee on Space Research (COSPAR)
|January 1, 1994
Summary
This study used a baboon model to investigate cardiovascular responses to microgravity. Findings show that heart filling pressures during microgravity depend on the animal's fluid volume status and body position.
Area of Science:
- Cardiovascular Physiology
- Space Medicine
- Animal Models
Background:
- Understanding cardiovascular adaptation to microgravity is crucial for astronaut health.
- Transient microgravity, induced by parabolic flight, offers a unique research opportunity.
- Previous studies have shown variable cardiovascular responses to microgravity.
Purpose of the Study:
- To evaluate central cardiovascular responses to transient microgravity using a chronically instrumented nonhuman primate model.
- To investigate the influence of circulatory volume status and body position on these responses.
Main Methods:
- Developed a baboon model with chronic instrumentation for simultaneous recording of cardiovascular parameters (pressures, blood flow, dimensions, ECG, pleural pressure).
- Conducted parabolic flight studies with animals in different volume conditions: volume depleted (DH), volume expanded (VE), and euvolemic (EU).
- Analyzed changes in right atrial pressure (RAP), left atrial pressure (LAP), and heart chamber areas during microgravity exposure.
Main Results:
- Right atrial pressure (RAP) responses to microgravity varied significantly based on volume status: decreases in DH (-10 mmHg upright, -3.2 mmHg supine) and increases in VE (+13 mmHg upright, +4.25 mmHg supine).
- Euvolemic (EU) animals showed an increase in RAP (+6.9 mmHg upright).
- Left atrial pressure (LAP) changes mirrored RAP but were more variable; heart chamber areas paralleled pressure changes.
Conclusions:
- Central cardiovascular filling pressures during sudden entry into microgravity are significantly influenced by the initial circulatory volume status.
- Body position (supine vs. upright) also modifies these cardiovascular responses.
- The baboon model provides valuable insights into human cardiovascular adaptation to microgravity environments.