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Plasma volume expansion in rats: effects on thermoregulation and exercise
R P Francesconi1, M Bosselaers, C Matthew
1US Army Research Institute of Environmental Medicine, Natick, Massachusetts 01760-5007.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|April 1, 1989
Summary
Polyethylene glycol (PEG) expanded plasma volume (PV) in rats, significantly increasing exercise endurance and improving thermoregulation in warm environments. This plasma volume expansion enhanced performance and heat management during physical activity.
Area of Science:
- Physiology
- Exercise Physiology
- Pharmacology
Background:
- Exercise in warm environments poses challenges to thermoregulation and performance.
- Plasma volume expansion is a potential strategy to mitigate these challenges.
Purpose of the Study:
- To investigate the effects of polyethylene glycol (PEG)-induced plasma volume expansion on exercise performance and thermoregulation in rats exposed to a warm environment.
Main Methods:
- Adult male rats were administered polyethylene glycol (PEG) or saline.
- Rats underwent treadmill exercise in a warm environment.
- Plasma volume, endurance, water loss, and thermoregulatory responses were measured.
- Atropine was administered to assess its effects on these parameters.
Main Results:
- PEG administration increased plasma volume by approximately 20% and significantly enhanced exercise endurance (from 67.9 to 93.6 min).
- Total water loss was increased in PEG-treated rats, while atropine reduced endurance and salivary water loss.
- PEG treatment reduced hematocrit and circulating protein levels, indicating hemodilution, without negatively impacting heat/exercise injury markers.
Conclusions:
- Expansion of plasma volume using PEG offers significant benefits for exercise performance and thermoregulation in warm conditions.
- PEG-induced hemodilution appears to be a viable strategy for improving physiological responses during heat and exercise stress.