title: Thermoregulatory defect in rats during anesthesia.
abstract: Male rats of the Fischer 344, Sprague-Dawley, Brattleboro, and Wistar strains, balb/C mice, and Hartley guinea pigs were divided into 2 treatment groups. One group drank tap water while the other group drank water containing 1 mg/ml of phenobarbital. Animals were exposed to sevoflurane, enflurane, methoxyflurane, isoflurane, or halothane in a closed chamber. In some of the experiments, soda lime was included and in other the chamber was heated to 39 degrees C with a water blanket. Eighty-six percent (43/50) of Fischer 344 rats treated with phenobarbital and esposed to either sevoflurane or enflurane, in the presence of either soda lime or exogenous heat, died within a few hours after exposure. Fischer 344 rats and rats of other strains drinking phenobarbital water and exposed to methoxyflurane were affected, but to a lesser degree. Rats drinking ordinary tap water and phenobarbital-treated rats not exposed to either soda lime or exogenous heat were unaffected. Guinea pigs and mice also were unaffected. We postulate that the toxic response represents a species-specific thermoregulatory defect, precipitated by heat and occurring in rats treated with phenobarbital in combination with sevoflurane, endlurane, or methoxyflurane.
mesh_terms: D000768:Anesthesia, General; D000777:Anesthetics / Q000009:adverse effects*; D000818:Animals; D004347:Drug Interactions; D004737:Enflurane / Q000009:adverse effects; D004987:Ethers / Q000009:adverse effects*; D006168:Guinea Pigs; D006221:Halothane / Q000009:adverse effects; D006845:Hydrocarbons, Fluorinated / Q000009:adverse effects; D007530:Isoflurane / Q000009:adverse effects; D008297:Male; D008305:Malignant Hyperthermia / Q000209:etiology*; D008733:Methoxyflurane / Q000009:adverse effects; D051379:Mice; D008807:Mice, Inbred BALB C; D010634:Phenobarbital / Q000009:adverse effects; D051381:Rats; D011916:Rats, Inbred F344; D013045:Species Specificity; D013997:Time Factors
chemical_list: D000777:Anesthetics; D004987:Ethers; D006845:Hydrocarbons, Fluorinated; D008733:Methoxyflurane; D004737:Enflurane; D007530:Isoflurane; D006221:Halothane; D010634:Phenobarbital