Hexose monophosphate shunt metabolism in sheep: comparison of fetal, newborn and adult erythrocytes.

Glucose utilization through the hexose monophosphate shunt was measured in erythrocytes from fetal sheep, newborn lambs and adult pregnant sheep. Fetal erythrocytes demonstrate dramatically increased glucose oxidation in the presence of the oxidant new methylene blue. This response declines by birth and thereafter until adult sheep erythrocytes show no response. No stimulation was observed in adult sheep red cells under a number of conditions, although when adult sheep red cells were separated according to cell age, young cells were found to respond greatly to new methylene blue. When the rate of glucose oxidation after new methylene blue stimulation is correlated with in vitro glucose-6-phosphate dehydrogenase activity, a highly significant relationship is seen. This suggests that developmental changes in glucose oxidation by sheep red cells may be due to similar changes in glucose-6-phosphate dehydrogenase activity. The relationship also suggests that mature adult erythrocytes may be unable to respond to oxidants because of their low glucose-6-phosphate dehydrogenase activity.