Ultrastructural studies of the hepatocytes after chronic exposure to low levels of halothane.

Adult rats were exposed to 10 ppm or 500 ppm halothane 8 hr/day and 5 days/wk for 8 wk or 4 wk, respectively. In the liver from animals which were exposed to 10 ppm of halothane, the rough endoplasmic reticulum in some hepatocytes accumulated a floccular, electron-dense material which gave the hepatocytes a dense and dark appearance. Increase in the matrical density and C-shaped transformation were observed in the mitochondria of some hepatocytes. In addition to these findings, areas of focal cytoplasmic degradation, dilatation of the bile canaliculi, peribiliary accumulation of lysosomes, and extensive dilatation of the smooth endoplasmic reticulum to form large cytoplasmic vacuoles were also observed in the hepatocytes of animals which had been exposed to 500 ppm halothane. Toxic potential of halothane upon chronic exposure is suggested.