[Patterns of the redistribution of sodium, potassium and water in the tissues of lactating white mice].

The Na+ concentration on the blood plasma of lactating mice increased by 22%. The muscle ion and water contents were unchanged in lactation whereas K+ level was increased by 15% in the red cells, the Na+ concentration - by 23% in mammary alveolar tissue, K+ - 2.5 times and water - 1.5 times as high as non-lactating animals. The data obtained suggest that: 1) the mechanism maintaining the cell Na+ concentration is sufficiently effective in lactation, 2) there is an interrelationship between the cell ion-water content and the degree of the rise in specific activity of the tissue during lactation, 3) Na+ enters the milk by a paracellular way in the mouse mammary gland in vivo after suckling.