[Perinatal development of the pyruvate metabolism-regulating enzyme in the pig liver]

The gluconeogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate carboxylase (PC) and the glycolytic enzyme pyruvate kinase (PK), regulating pyruvate metabolism, were determined in the livers of 71 fetuses, which were developed of 25 dams on the 80th, 100th, 106th, and 112th day of gestation (length: 115 days) by Caesarean section. For comparative purposes the same enzymes were estimated in 12 naturally born piglets immediately after delivery. During the period under examination (the last third of gestation) the total activity of PEPCK has its highest values at the 80th day, the PC and PK activity at the 100th day of gestation. The activities of all 3 enzymes decrease during the last 2 weeks of gestation until birth. The cytosolic part of PEPCK amounts to 10-15 per cent of total activity and develops in a parallel manner. In newborn piglets a further decline of the PC and total PEPCK activity can be observed, but the cytosolic PEPCK activity remains constant, and therefore its relative proportion increases to 25% of the total activity. The PK activity rises distinctly (1.5 times). The role of these enzymes in the carbohydrate metabolism of the fetus, especially in gluconeogenesis, is discussed in detail.