[Cell kinetic studies on the interference between proliferative and functional metabolism in regenerating rat liver after application of phenobarbital (author's transl)]

To investigate the correlation between fuction and proliferation, cell kinetic studies were carried out in regenerating liver of phenobarbital (PB) treated rats. Male adult Wistar rats received i.p. injections of 90 mgPB/kg body weight daily for five days (group A). Rats of group B received additional injections of PB at a reduced dose (30mg/kg) every 12 hrs after partial hepatectomy, starting immediately after the operation. 60 min after a single injection of 3-H-TdR at different intervals after surgery, specific activity of DNA, 3=H=TdR labeling index, and mitotic index were determined. Intralobular distribution of DNA-synthesizing hepatocytes was analyzed in 22 h regenerating liver. Stimulation of fuctional activities by PB results in a transitional synchronization of the start of DNA synthesis in liver parenchymal cells after partial hepatectomy. The labeling indices of group A and B increase to 36% and 30%, respectistribution of DNA-synthesizing hepatocytes revealed that higher levels of synchronization are limited to periportal zones of the liver lobule which provide optimal conditions of G1-S transition. PB treatment apparently does not influence duration of S,G2 or M under these conditions. The results stress the possibility that transitional synchronization of DNA synthesis by functional load might simulate stimulation of growth in a proliferating population.