Changes of body fluids and ions in cold‐adapted subjects

Abstract

To characterize fluid and ion shifts during a 4‐week cold adaptation period, six nonadapted volunteers underwent a cold acclimation program (CAP), which consisted of 1 hour head‐out immersion in water 14 ± 1°C three times a week. Blood samples were analyzed before and after immersion in the first and last weeks of CAR Urine was collected for 10 hours before, during, and for 3 hours after immersion. Plasma volume (PV) decreased during the first immersion (‐18%) and less after CAP (‐12%). Blood volume reduction was 8.5% before and 5.2% after CAP. Mean corpuscular volume was not changed either after the cold exposure or after the cold adaptation. The concentration of serum proteins increased by 12.1% after first immersion and by 8.1% after CAP. The changes in serum concentration of Na⁺, K⁺, and Cl^‐ before and after CAP were not significant. Urine flow increased by 97% after the first immersion, and by 165% after CAR Urinary excretion of Na⁺ increased by 65% and 184% and of K⁺, by 122% and 262% during first immersion and after CAP, respectively. Serum concentration of aldosterone increased nonsignificantly (+30%) during immersion before CAP and it did not change after CAR A significant reduction in PV and an increased diuresis and elevated excretion of cations occurred after CAP.