Intracellular ionic changes during hyperthermia of tumor cells in the presence of lanthanum.

The experimental data suggest that permeability changes at the plasma membrane level are the most likely cause of the enhancement of tumor cell killing by hyperthermia in the presence of 1 mM La3+. The interaction of La3+ with the Na+, K+ ATPase and Ca2+-pump ATPase may be the probable cause of dramatic electrolyte changes which enhance the hyperthermia effects on tumor cells.