[Formation of the ion-depositing function of rat tissues during ontogenesis].

In experiments on rats of two age groups (adult animals older 180 days and young ones ageing between 18 and 28 days), studies have been made of ion-accumulating function of various tissues. It was shown that after the administration to animals of salt load (10% solution of NaCl, 50 mg/kg of body weight) changes take place in the concentration of cations and in the content of dry material of the blood plasma. The pattern and the magnitude of these changes depend on the age of animals. Salt loading in adult animals resulted in the significant increase in tissue Na, insignificant increase in tissue K and the decrease in water content. Na-accumulating capacity is different in various tissues. In tissues of young rats, similar loading does not significantly affect the content of ions and water. It is suggested that ion-accumulating capacity of the tissues is absent in early postnatal ontogenesis of rats.