The ratio of albumin synthesis to total protein synthesis in normal rat liver, in host liver, and in Morris hepatoma 9121.

Radioactive leucine was injected into the cavai vein of normal and Morris hepatoma 9121-bearing rats. Livers and hepatomas were removed 12 min later. Within this time, no newly synthesized radioactive protein had left the liver, since labeled protein appeared in the blood no earlier than 15 min after injection. Albumin was purified from livers and hepatomas to constant specific radioactivity. The specific radioactivity of albumin purified from normal liver was 100 times higher than that of albumin from tumor. In normal liver, the radioactivity incorporated into albumin was 3.7% of that found in total protein. In host liver, 2.8% of total protein radioactivity was found in albumin, and in hepatoma only 0.36% of labeled leucine incorporated into protein was measured in albumin. The protein turnover is slower in Morris hepatoma 9121 than in liver; hence, albumin synthesis is strongly decreased in Morris hepatoma 9121 as compared to liver.