Net sodium and potassium movements in liver slices prepared from rats of different foetal and post-natal ages

Abstract

1.1. Net movements of sodium and potassium in liver slices prepared from rats at different stages of foetal and post-natal growth have been studied in vitro.2.2. During incubation at 1° slices prepared from rats of most of the ages studied lost potassium and gained sodium and water. These changes could be accounted for by a 1:1 exchange of Na+ from the medium for K+ of the cells and by the further entry of sodium as a solution having the same composition as the medium.3.3. In liver slices from the youngest rats studied (17–18 days gestation) the extent of the changes during incubation at 1° was much less than in slices prepared from older animals. There was no significant increase in the water content and the net gain of sodium was equivalent to the loss of potassium.4.4. During subsequent incubation at 38° under aerobic conditions the slices from rats of all ages regained potassium and lost sodium.5.5. The net uptake of potassium during the incubation at 38° of liver slices prepared from foetuses at 17–20 days gestation was completely inhibited by cyanide. At 21–22 days gestation about 40% of the potassium uptake persisted in the presence of cyanide; after birth about 10% of the potassium uptake was resistant to cyanide. The cyanide-resistant potassium uptake was inhibited by the further addition of iodoacetate to the incubation medium.6.6. Liver slices prepared from foetuses at 17–20 days gestation showed a net loss of sodium during incubation at 38° in the presence of cyanide.7.7. The relation of the sodium and potassium movements at 38° to the respiratory and anaerobic glycolytic activity of the rat liver during the growth of the animal is discussed.