Mobilization of amino acids in tumor cells by hyperthermia

When p815 mastocytoma cells are heated to 43 degrees C from 37 degrees C, pools of individual amino acids and the total amino acid pool increase significantly, the latter reaching a new plateau within 20 minutes. The increase in the total amino acid pool may reach as much as 75 mOsm per liter of cell water or 26% of the cellular osmolarity. The source of this excess amino acid is not due to an accelerated degradation of proteins, but either to the amino acids left behind by slowed protein synthesis or to the accelerated transport of extracellular amino acids into the cell. The excess amino acid should increase the osmolarity and the cell volume. Evidence suggests that the cell volume increase triggers the osmoregulatory process to reduce the contents of major ions.