Azathioprine treatment increases hepatocyte turnover.

The effect of azathioprine on the hepatocytes cell turnover was evaluated. This was accomplished by injection of rats with trituim thymidine. The distance of labeled liver cells from the portal space was determined, after 1 hour and 30 days, in control and azathioprine-treated rats. In the control group, the streaming velocities of hepatocytes and littoral cells were 3.2 microns/day and 3.1 microns/day, respectively. In azathioprine-treated animals, the respective velocities were 7.0 microns/day and 5.5 microns/day. In the liver acinus, cell displacement velocity is proportional to cell production. Because hepatocyte velocity in azathioprine-treated animals increased by 218% and littoral cell velocity by 177%, their respective turnovers also increased to 218% and 177%. It can be concluded that the liver is essentially a slowly renewing cell population. Azathioprine increased the hepatocytes' and littoral cells' streaming velocities. This in vivo experimental model may help evaluate the effect of hepatotoxic drugs on the kinetics of liver cells.