[Concentration of potassium and sodium in the white and red muscles of the rat during adaptation to cold].

The K+ and Na+ contents changes considerably in cold adaptation only in the rat white neck muscles, remaining the same in the red muscles of hind-limbs. The ratio of K+/Na+ intracellular concentration gradually reduced from 19.8 +/- 1.7 prior to the adaptation to 12.6 +/- 1.4 within 9 weeks of the cold adaptation.