OXYGEN-DEPENDENT REGULATION OF ENERGY-METABOLISM IN ASCITES TUMOR-CELLS BY NITRIC-OXIDE

To understand the role of nitric oxide (NO) in the regulation of energ y metabolism of tumor cells, its effect on the respiration and calcium homeostasis was examined with ascites hepatoma (AH130) cells under di fferent oxygen tensions. NO reversibly inhibited the respiration and d epolarized the membrane potential of AH130 cells in an oxygen-dependen t manner; the inhibition was more marked at physiologically low oxygen concentrations than at its high tensions. NO reversibly decreased the cellular ATP Levels and elevated the cytosolic calcium, particularly under low oxygen concentrations. Since the peritoneal cavity is fairly anaerobic, the results suggested that small amounts of NO generated i n this compartment might strongly affect the energy metabolism and cal cium homeostasis of tumor cells in vivo.