Thermoregulatory responses of the rabbit to subcutaneous injection of sulfolane.

Earlier studies have shown that intraperitoneal injection of the industrial solvent sulfolane (tetrahydrothiophene-1,1-dioxide) caused a decrease in metabolic rate and a rapid, regulated hypothermia in mice and rats. In the present study, subcutaneous injections of 0, 100, 200, 400, 600, and 750 mg/kg sulfolane at an ambient temperature (Ta) of 10 degrees C caused a dose-dependent decrease in colonic temperature (Tc) of rabbits. Metabolic rate (MR) remained unchanged during the initial phase of the hypothermia for all dose groups; but peripheral vasodilation, as indicated by an increase in ear skin temperature, was seen at the higher dose levels. The observed thermoregulatory response to sulfolane was a function of Ta. Thus, at Tas of 10 and 20 degrees C, injection of 600 mg/kg sulfolane had no effect on MR but caused an increase in ear skin temperature. The magnitude of the hypothermia was similar at these two Tas, indicating the sulfolane-treated rabbits had some control over Tc. At a Ta of 28 degrees C, however, the animals became hyperthermic upon injection of 600 mg/kg sulfolane.