Salicylate hypothermia in rats exposed to hyperbaric air and helium.

Rectal temperatures of salicylate-treated and untreated rats were observed in 21-23 degrees C air at 1, 3, 6, and 8 ATA, in 21-23 degrees C helium at 1 and 6 ATA, and in 1 ATA thermal neutral air (28 degrees C). Significant dose-related temperature decreases occurred in 21-23 degrees C 1 ATA air with 180 and 300 mg/kg of salicylate; 60 mg/kg had no effect. However, in thermal neutral air, 300 mg/kg significantly elevated temperatures. Hyperbaric air and helium had temperature-lowering effects which were correlated with thermal properties of these environments, and in them the hypothermic effects of salicylate were similar to those in 1 ATA air, the total temperature decreases being the sum of the salicylate hypothermia and that caused by the hyperbaric air or helium. These additive temperature effects are unlike previously reported results in which the temperature lowering effects of 5 degrees C cold exposure and salicylate together were greater than the sum of the two individual effects.