Initial rate of sodium taurocholate uptake in isolated elutriated hepatocytes from untreated and phenobarbital-treated rats.

The initial rate of sodium taurocholate uptake was measured in rat hepatocytes separated by centrifugal elutriation into five cell fractions whose difference in size was verified by flow cytometry. The hepatocytes were prepared from untreated and phenobarbital-treated rats. For untreated animals, the initial rate of taurocholate uptake at concentrations of 5 or 50 microM was the same for hepatocytes prior to fractionation and for each of the five elutriated fractions. Treatment of the animals with phenobarbital was associated with a significant increase in hepatocyte size in all fractions and caused a significant increase in the initial uptake rate. The extent of the rate increase in hepatocytes prior to fractionation was similar to that observed for each of the five hepatocyte subpopulations. Our observation indicates that phenobarbital causes a significant increase in the initial rate of sodium taurocholate uptake and suggests that large and small hepatocytes possess no inherent differences controlling the initial uptake process.