Evaluation of the effect of arginine-enriched amino acid solution on tumor growth.

To investigate the effect of arginine-enriched solution on tumor growth and metastasis, rats were infused with solutions containing 5.5 and 0.66% arginine for 8 days. Infusions were started at the same time of subcutaneous transplant of Yoshida sarcoma. Arginine-rich solution suppressed tumor growth at an early stage and prevented metastases to the liver and kidney. In addition, arginine supplements enhanced the phagocytic activity of alveolar macrophages. It also resulted in maintenance of a positive nitrogen balance and prevented the increases in the levels of several amino acids observed in the control group. The suppressive effect of arginine-enriched solution on tumor growth may be due to its activation of the immunologic system, in which the phagocytic activity of macrophages probably participates.