Effect of mild whole body hyperthermia on cytotoxic action of N-methyl-N′-nitro-N-nitrosoguanidine in Swiss mice

Studies were carried out to ascertain the efficacy of mild whole body hyperthermia (WBH) as a modifier of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) cytotoxicity in mice. Adult Swiss male mice, 6-8 weeks old, weighing about 25 g were exposed to mild WBH (39°C, 1 h) in a precision temperature controlled environmental chamber maintained at 50-60% relative humidity. Twenty-four hours after treatment, animals were administered with different doses of MNNG either by intraperitoneal (i.p.) injections or by feeding through drinking water and were monitored for survival. The studies revealed that the exposure of animals to mild WBH, 24 h prior to MNNG administration results in an increase in survival and recovery in mean body weight compared with those administered with MNNG only. This suggests that prior WBH treatment can effectively reduce the MNNG cytotoxicity in mice.