Local anaesthetics as hypoxic radiosensitizers, oxic radioprotectors and potentiators of hyperthermic killing in mammalian cells.

Local anaesthetics with well-known pharmacology are found to radiosensitize hypoxic and radioprotect oxic murine L5178Y cells. Under the specified experimental conditions, radiation-modifying effects exerted by local anaesthetics are dose-dependent. It appears that in order that the drugs should act as oxic radioprotectors or as hypoxic radio-sensitizers, the agent must be present during the period of irradiation. Local anaesthetics are also found to potentiate the hyperthermic killing of cells. The possibility of applying compounds with such dual radiation-modifying properties plus hyperthermia-potentiating capacity to enhance the therapeutic gains in tumour therapy is briefly discussed.