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Pulmonary blood flow redistribution by increased gravitational force
M P Hlastala1, M A Chornuk, D A Self
1Department of Physiology and Biophysics, University of Washington, Seattle 98195, USA.
Summary
Gravity significantly impacts pulmonary blood flow distribution in swine lungs. Increased gravitational force, or Gx, augmented blood flow gradients, contrary to existing models.
Area of Science:
- Physiology
- Cardiovascular Research
- Aerospace Medicine
Background:
- Gravity's influence on bodily fluid distribution is well-established.
- Understanding pulmonary blood flow (PBF) under altered gravity is crucial for spaceflight and high-G environments.
Purpose of the Study:
- To investigate the effects of increased inertial force (Gx) on pulmonary blood flow distribution in unanesthetized swine.
- To assess the role of gravity in PBF heterogeneity and compare findings with the zone model.
Main Methods:
- Unanesthetized swine were exposed to -1, -2, and -3 Gx on a centrifuge.
- Pulmonary blood flow distribution was measured using fluorescent microspheres.
- Pulmonary vascular pressures, cardiac output, heart rate, and blood gases were monitored.
Main Results:
- PBF heterogeneity, measured by the coefficient of variation, increased with higher Gx levels.
- A distinct gradient of PBF from ventral to dorsal and cranial to caudal regions was observed and amplified by Gx.
- Extrapolation suggested a slight dorsal dominance of PBF in microgravity.
Conclusions:
- Gravity significantly influences PBF distribution, augmenting regional gradients.
- Vascular structure accounts for the majority of PBF variance, but gravity plays a notable role.
- The observed PBF distribution patterns challenge the predictions of the traditional zone model.
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