[Space-time characteristics of the activity of beta-hydroxybutyrate dehydrogenase in the rat liver lobule].

Experiments were made on normal male rats weighing 180-200 g kept over 2 weeks before sacrifice in the light (12 h) and in the dark (12 h). The activity of beta-hydroxybutyrate dehydrogenase (BDH) in hepatocytes was detected by histochemistry. The quantitative determination of the enzymatic activity (EA) was performed on a scanning cytophotometer. The whole lobule, its zones and subzones demonstrated circadian rhythms of EA with a maximum being attained at 9 and minimum at 21 o'clock. The circadian rhythms were also inherent in the mean magnitude of EA changes per cell position both in the whole lobule and its zones. Unlike circadian rhythms of the absolute indices of EA, these rhythms in the lobular zones were discovered to be asynchronous. The maximum magnitude of EA changes from cell to cell manifested circadian rhythms characterized by its spatial displacement through the lobular zones. The highest absolute values of EA were seen in the central parts of the lobule decreasing towards the periphery. It is suggested that the functional heterogeneity of hepatocytes changes in space and time.