Sensitization of Anoxic Mouse Tumours to X-rays with Diamide and Nifuroxime

Abstract

Injection of diazenedicarboxylic acid bis (N,N′-dimethylamide) (‘diamide’) into ascitic P388 murine lymphocytic leukaemia tumours and solid EMT6 carcinomas oxidized their endogenous non-protein sulphydryl content. A nontoxic dose of the compound injected directly into the tumour sensitized anoxic P388 tumours to X-radiation (DMF = 1·82) but had no effect on EMT6 tumours; failure to sensitize the EMT6 may be due to metabolic consumption of diamide by the solid tumour. Intravenous injection of diamide or of nifuroxime alone had no effect on anoxic EMT6 tumours, nor had a combination of both administered 10 min before irradiation. When the interval between injection of the diamide-nifuroxime solution and irradiation was lengthened to 30 min, however, some sensitization occurred. These results indicate that diamide can sensitize in vivo under some conditions and suggest that better results might be obtained with combinations of radiosensitizing agents than with single compounds.