Effect of sulfolane on behavioral and autonomic thermoregulation in the rat.

Sulfolane (tetrahydrothiophene 1,1-dioxide), a commonly used extraction solvent, promotes rapid changes in the thermoregulatory system. Colonic temperature, skin temperature, metabolic rate, and preferred ambient temperature (Ta) were measured over an 8-h period in the Sprague-Dawley rat following an intraperitoneal injection of sulfolane at 800 mg/kg or of physiological saline. At Ta values of 15 and 25 degrees C, sulfolane caused a significant inhibition in metabolic rate and reduction in colonic temperature, which lasted over the 8-h measuring period. At both Ta values, metabolic rate tended to recover approximately 4 h after sulfolane injection. Colonic temperature recovered with time but was still significantly reduced at 8 h postinjection. Tail skin temperature was unaffected. Preferred Ta in the sulfolane-treated rat was not significantly different from the controls. In spite of their hypothermic condition, the sulfolane-treated animals did not select a warm Ta. Since sulfolane toxicity appears to be greater with increased tissue temperature, the sulfolane-induced hypothermia may enhance survival of the rat following exposure to toxic levels of sulfolane.