Effects of liver ischemia on degradation of different classes of hepatic proteins

The effects of liver ischemia on hepatic protein degradation were studied in rats. In one series of experiments degradation was measured in incubated liver slices as release of trichloroacetic acid soluble radioactivity from proteins prelabelled with L-(¹⁴C)-leucine during 4 h (short-lived proteins) or during 24 h (long-lived proteins). In another series of experiments protein degradation was determined in vivo by measuring decay of radioactivity in hepatic proteins prelabelled with (¹⁴C)-sodium bicarbonate administered intraperitoneally 4 h or 24 h before induction of liver ischemia. Degradation of short-lived proteins was reduced by 50% both in vitro and in vivo during liver ischemia while breakdown of long-lived proteins was unchanged. Thus, short-lived and long-lived proteins were differently affected by liver ischemia. These results are consistent with the concept of distinct proteolytic pathways for different classes of proteins.