Protein synthesis in liver and skeletal muscle of mice bearing an ascites tumor.

In mice bearing an ascites tumor at an advanced stage of growth, the weight of the gastrocnemius muscle fell, whereas that of the liver increased. Fractional rates of protein synthesis were measured in vivo under conditions designed to minimize uncertainties in the determination of the specific radioactivity of the precursor amino acid pool. Protein synthesis in liver increased in the tumor-bearing mice in comparison with controls either fed ad libitum or pair-fed to the reduced food intake of the tumor-bearing group. In muscle, the rate of protein synthesis fell substantially in comparison to ad libitum-fed controls but was not significantly different from that in a group for which food intake was restricted to that of the tumor-bearing animals.