Perinatal development of the distributions of phosphoenolpyruvate carboxykinase and succinate dehydrogenase in rat liver parenchyma.

Parenchymal distributions and activities of mitochondrial succinate dehydrogenase and cytosolic phosphoenolpyruvate carboxy-kinase were studied during perinatal development of rat liver. 1. Succinate dehydrogenase activity increased almost linearly from day 5 before to day 5 after birth. Hepatocytes with higher enzyme activities were disseminated heterogeneously, zonal heterogeneity developed during the second week. 2. Cytosolic phosphoenolpyruvate carboxykinase was not detectable before birth; it was induced to high levels during day 1 and increased further to a maximum during days 5 to 10. It decreased again to adult levels at the end of the third week. The enzyme distribution already showed signs of a zonal heterogeneity at day 1, which became fully developed during the second week. The results indicate that the zonal heterogeneity typical of adult liver was established for the two enzymes during the second week of life. They revealed in addition that the two enzymes, representing two different subcellular compartments, had an individual development towards the zonal heterogeneity.