INDUCTION OF DIFFERENTIATION BY RADIATION AND HYPERTHERMIA IN NEUROBLASTOMA-GLIOMA HYBRID-CELLS

The effects of either radiation or hyperthermia on the differentiation potential of NG108-15, a neuroblastoma-glioma hybrid cell line, were studied. After radiation and hyperthermia, the outgrowth of neurites f rom NG108-15 cells was potentiated, and polarizing current and voltage pulses induced a distinct action potential and a diphasic (inward fol lowing outward) current, respectively. An increase in the specific act ivity of acetylcholinesterase was also observed. In addition, both tre atments induced an elevation of the concentration of intracellular cal cium in some cells. The increase in intracellular calcium concentratio n caused by applying the calcium ionophore, A23187, induced differenti ation. It is suggested that both the radiation- and the hyperthermia-i nduced increases of electrical excitability and acetylcholinesterase a ctivity may have originated from an increase in intracellular Ca2+ con centration.