[Carbohydrate metabolism in rabbit livers in the pre- and post-natal period]

Until the 25th day of gestation only traces of glycogen are present in the fetal liver of rabbits. Then, a steep rise can be observed until birth. The prenatal accumulation of glycogen protects the newborn against glucose deficiency after the sudden interruption of glucose supply after birth. Immediately after birth the blood glucose level falls in newborn rabbits. With insufficient gluconeogenesis stabilization during the first hours of postnatal life depends on the extent of the glucogen storage in the liver. The HK of the rabbit liver shows a higher activity during the fetal period as compared to the postnatal period. During postnatal life the relative proportion of the HK of the phosphorylation of glucose shows a consistent decrease; and in adult animals this function is nearly entirely taken over by the GK. In accordance with the occurrence of a GK activity the glycogen content shows a steep increase in the rabbit liver after the 9th day of life. The high PK activity of the fetal liver suggests a high glycolytic activity. The decrease in activity during the first days of life favours the overshooting gluconeogenesis of this phase and thus might contribute to the stabilization of the glucose blood level. The rise of activity at the 9th day of life shows a nearly synchronous behaviour in comparison with the development of the GK activity. Due to the change of food with introduction of solid nutrition rich in carbohydrates the PK shows a new rise after the 21st day of postnatal life. Whereas the activity of LDH of the fetal liver of rabbits is of the same magnitude as that of adult animals, there is a perinatal increase of activity with a peak at the 9th day of postnatal life. This step-up of activity is regarded as an adaptation phenomenon by de novo synthesis of enzyme protein.