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Reversal of cold induced haemoconcentration
P Vogelaere1, G Savourey, G Deklunder
1Life Fitness Center, Vrije Universiteit Brussel, Belgium.
Summary
Cold exposure reduces plasma volume, but this effect is reversible. Increased blood pressure may cause plasma water to shift from vascular to interstitial spaces, explaining this reversal.
Area of Science:
- Physiology
- Environmental Medicine
Background:
- Cold-induced plasma volume reduction is traditionally attributed to inhibited antidiuretic hormone release and increased diuresis.
- The reversibility of cold-induced hemoconcentration during rewarming challenges this traditional explanation.
Purpose of the Study:
- To investigate the mechanisms underlying the reversal of cold-induced hemoconcentration.
- To elucidate the physiological responses to cold stress and subsequent rewarming.
Main Methods:
- Six young males underwent controlled exposure to a cold environment (1°C) and a thermoneutral environment.
- Plasma volume, osmolality, and urine production were monitored during cold stress and a 60-minute recovery period.
Main Results:
- Cold stress caused a 15% (510 ml) reduction in plasma volume with unchanged osmolality.
- During recovery, plasma volume reduction decreased to 3% (100 ml), matching increased urine production.
- Increased blood pressure during cold exposure may induce a transient shift of plasma water into interstitial spaces.
Conclusions:
- Cold-induced hemoconcentration is not solely explained by increased urinary water loss.
- A transient shift of plasma water from the vascular to the interstitial space, potentially due to elevated blood pressure, is implicated in the reversal of cold-induced plasma volume reduction.