A comparison of hepatocyte size distribution in untreated and phenobarbital-treated rats as assessed by flow cytometry.

Flow cytometric analysis of narrow forward angle light scatter was used to examine the effect of phenobarbital treatment on hepatocyte size. Light scatter analysis of freshly isolated hepatocytes and of hepatocytes separated by means of centrifugal elutriation into five subpopulations (fractions 1-5) was performed on both untreated and phenobarbital-treated rats. The frequency distribution histogram of forward scatter intensity produced by freshly isolated hepatocytes from untreated rats was used as the baseline. This histogram was arbitrarily divided into four regions; referred to as region 1 (small cells) to region 4 (large cells). Subsequent analysis of the light scatter histograms derived from elutriated fractions of both untreated and phenobarbital-treated animals was performed using these baseline regions. Analysis showed that small cells were enriched in elutriated fraction 1, and large cells in elutriated fraction 5. Phenobarbital treatment was associated with a uniform shift to a higher intensity light scatter (relative increase in cell size) within each of the four selected regions. Our findings suggest that phenobarbital does not have a selective hypertrophic effect on these subpopulations of rat hepatocytes.