The effect of oxidative injury on hepatocellular influx of leucine in the rat

The hepatocellular influx of leucine was investigated in the perfused rat liver using the multiple indicator-dilution technique. The cellular influx of leucine was saturable and the K_m and V_max values were 5.3 ± 1.8 mM and 194 ± 25 nmol/s/g of liver, respectively. These were similar to those reported in cell membrane preparations. Previous studies have indicated that oxidative injury impairs the activity of membrane transporters. Perfusion with 10 mM hydrogen peroxide for 3 min caused a significant reduction in leucine influx from 7.4 ± 1.4 nmol/s/g of liver to 4.6 ± 1.0 nmol/s/g of liver (P = 0.007) with a perfusate leucine concentration of 0.13 μM. This was not associated with any significant change in the extracellular volume (0.31 ± 0.08 ml/g of liver vs. 0.32 ± 0.01 ml/g of liver). This confirms that oxidative injury in the liver is associated with impairment of membrane transport and extends the observation to the transport of leucine.