Quantitative distribution of lactic dehydrogenase in the regenerating liver lobule of the rat.

Abstract

Regeneration of rat liver is maximal during the first day following partial hepatectomy. In order to obtain quantitative data on lactic dehydrogenase during this period of increased energy utilization, microdissection of lobules at 0, 15 and 30 hr after partial hepatectomy was carried out. Isolated samples from periportal, midzone and pericentral areas weighing 0.05-0.2 µg, dry weight, were analyzed for LDH and DNA. Sections were also stained for glycogen, fat and LDH. Qualitative results revealed depletion of glycogen from portal and midzonal regions, accumulation of fat in periportal zones, and heavier concentrations of LDH in peripheral areas of the regenerating lobule. Quantitative analysis showed LDH activity to be 40-50% higher in peripheral compared to central zones. Similar levels and relative concentrations of enzyme persisted throughout the 30-hr regenerative period investigated. DNA content increased by about 30% in the peripheral zone during the same period. The possible meaning of these findings is discussed.