EFFECTS OF CHRONIC INHALATION OF HALOTHANE, ENFLURANE OR ISOFLURANE IN RATS

Male Fischer 344 rats were exposed to halothane, enflurane orisoflurane vapour 20 p.p.m., or air, for up to 30 weeks. Noneof the anaesthetic agents led to hepatocellular necrosis. Exposureto halothane resulted in slight increases in serum alanine aminotransferaseactivity, an increase in the size of the liver, an increasein hepatic microsomal cytochrome P-450 content and a minimalamount of fatty change in the liver. None of these effects wereobserved during exposure to enflurane or isoflurane. Urinaryfluoride excretion was increased during exposure to either enfluraneor isoflurane. Using this increase as an index of anaestheticbiotransformation, we found that the extent of bsiotransformationof isoflurane was only slightly lower than that of enflurane. ^*Histopathology, Flinders Medical Centre, Bedford Park, SouthAustralia 5042