The role of metabolic energy in the maturation-associated loss of reticulocyte membrane transport.

The role of metabolic energy in cell maturation-associated loss of membrane functions has been studied using sheep reticulocytes incubated in vitro at 37 degrees C for periods up to 41 hours. ATP either was maintained with glucose, adenosine plus inosine or depleted with 2-deoxyglucose plus arsenate. Two membrane transport systems were studied: Na+-dependent glycine transport and the sodium pump, estimated from the number of specific [3H] ouabain binding sites per cell. Although both transport systems decreased during maturation, the decrease was much less in ATP-depleted cells compared to ATP-replete cells. The phenomenon is relatively specific: not all maturation-associated changes are similarly affected. Thus, the decreases in activity of the cytoplasmic enzymes glucose-6-phosphate dehydrogenase, hexokinase and phosphoglucose isomerase were not prevented by energy depletion. It is concluded that the loss of certain functions during reticulocyte maturation is retarded by metabolic depletion.