Distribution of a Non-Metabolizable Amino Acid in Different Tissues of Tumor-Bearing Rats in Cachexia

抄録

Amino acid uptake by various tissues in cancer cachexia was studied by determination of the intracellular/extracellular distribution ratios of the non-metabolizable amino acid analog α-aminoisobutyric acid (AIB) in the tumor tissue, liver, and skeletal muscle of three groups of 8 rats each: freely-feeding control rats (FF group), rats bearing methylcholanthrene-induced sarcomas for 26 days (TB group) and pair-fed control rats matched by carcass weight with TB rats (PF group). AIB uptake by the soleus muscle measured 1h after its injection was significantly less in PF and TB rats than in FF rats. On the other hand, AIB uptake by the liver was significantly higher in PF and TB rats than in FF rats. AIB uptake by tumor tissue was 1.5 times that by the liver of TB rats. These results suggest that in PF rats, which suffered severe starvation, tissue depletion was associated with low amino acid uptake by muscle and transfer of amino acids to the liver, whereas in TB rats with malignant malnutrition it was associated with low amino acid uptake by muscle with transfer of amino acids to the tumor tissue.