OXYGEN CONSUMPTION AND GLYCOLYSIS IN FETAL, NEONATAL, AND INFANT MUSCLE OF THE RHESUS MONKEY

Abstract

Muscle fiber groups from fetal, neonatal, infant, and adult rhesus monkeys (Macaca mulatta) were incubated in glycylglycine and bicarbonate buffered media plus glucose-C14. Results obtained with these two media were similar. The metabolic data were calculated with noncollagenous nitrogen as a reference base. Under aerobic conditions the QO2 and CO2 productions were higher at 89 to 90 days fetal age, similar at 120 to 129 days, and lower at 150 to 160 days than those of adult muscle. Glucose uptake was higher at 89 to 90 days and 120 to 129 days fetal age than that of the adult series. Variations in the above parameters demonstrate that results on fetal metabolism must be reported for specific gestational periods. Lactate and lactate-C14 productions were higher in all three fetal series, and pyruvate and pyruvate-C14 productions were higher in the earlier fetal series than in those of the adult. The sum of C14 activities appearing in lactate, pyruvate, and CO2 was higher in rapidly growing muscle than in adult muscle. These data suggest that aerobic glycolysis is more active in fetal and neonatal than in adult muscle. Birth did not cause a significant change in any metabolic parameter. The relative increases, under hypoxic conditions, in glucose uptake and lactate and lactate-C14 productions in fetal compared with the increases in adult muscle suggest that the glycolytic pathway of fetal muscle does not respond more effectively to hypoxia.