THE EFFECT OF OXIDATIVE INJURY ON HEPATOCELLULAR INFLUX OF LEUCINE INTHE RAT

The hepatocellular influx of leucine was investigated in the perfused rat liver using the multiple indicator-dilution technique. The cellula r 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 wer e similar to those reported in cell membrane preparations. Previous st udies have indicated that oxidative injury impairs the activity of mem brane transporters. Perfusion with 10 mM hydrogen peroxide for 3 min c aused 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 perfu sate leucine concentration of 0.13 mu M. 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 oxidati ve injury in the liver is associated with impairment of membrane trans port and extends the observation to the transport of leucine.