Autoradiographische Untersuchungen über intralobuläre Differenzen der Flu\rate von Hepatocyten in das S-Kompartiment in Frühstadien nach partieller Hepatektomie

Kinetics of hepatocellular proliferation as a function of the microvascular structure and functional state of the liver

An analysis of hepatocellular proliferation in regenerating rat liver reveals a dependence of kinetic parameters on the microvascular structure of the liver. Influx kinetics of hepatocytes into DNA synthesis as well as cell cycle phases vary in different parts of the liver lobule between the afferent and efferent vascular poles. Heterogeneity of the proliferative response and size limitations on cell cycle compartments appear to be intimately related to the actual functional state of the individual liver cell. Modifications of liver cell functions result in variations of the proliferative activity. Phenobarbital-induced hypertrophy of hepatocytes reveals a permissive action on G1- S influx. Selective destruction of the subpopulations, by allyl formate, leads to a new functional determination of the residual liver and to a change in proliferative compartments. Maximum modulation of cell cycle compartments is obtained by hydroxyurea-induced synchronization of hepatocytes after partial liver resection. During hydroxyurea treatment, the regenerating liver shows a pronounced cellular hypertrophy. After release from hydroxyurea block, cells embark on DNA synthesis simultaneously. The DNA synthesizing compartment comprises almost the entire liver cell population. Heptotrophic factors might play a part in regulating or modifying hepatocellular function and proliferative response after cell loss.

Analysis of cell cycle compartments of hepatocytes after partial hepatecomy

An analysis of cell kinetic parameters as a function of intralobular localization of hepatocytes was performed using autoradiographic methods to obtain a basis for a quantitative description of cell cycle compartments after partial hepatectomy. The influx into the S compartment revealed a maximum in a lobular zone not immediately adjacent to the portal tract, with a decrease towards the perivenous and periportal area of the lobule. The maximum influx was found in the intermediate zone at 34 hr and a lower one in the perivenous parts of the lobule at 40 hr. The influx pattern at 56 hr was similar to the situation at 18 hr. The fraction of labelled mitoses in the whole liver and in subunits of the lobule disclosed a constant duration of S whereas the duration of G2 + M was prolonged from the periportal to the perivenous zone. A graphical model of kinetic events after partial hepatectomy is proposed, which describes the sizes of the various cell cycle compartments; the model successfully predicted the results of a continuous labelling experiment.