Genotoxicity of inhalation anesthetics halothane and isoflurane in human lymphocytes studied in vitro using the comet assay

Mutat Res. 1999 Feb 19;439(2):199-206. doi: 10.1016/s1383-5718(98)00195-8.


The alkaline single cell gel electrophoresis (comet) assay was applied to study genotoxic properties of two inhalation anesthetics-halothane and isoflurane-in human peripheral blood lymphocytes (PBL). The cells were exposed in vitro to either halothane (2-bromo-2-chloro-1,1,1-trifluoroethane) or isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether) at concentrations 0.1-10 mM in DMSO. The anesthetics-induced DNA strand breaks as well as alkali-labile sites were measured as total comet length (i.e., increase of a DNA migration). Both analysed drugs were capable of increasing DNA migration in a dose-dependent manner. In experiments conducted at two different electrophoretic conditions (0. 56 and 0.78 V/cm), halothane was able to increase DNA migration to a higher extent than isoflurane. The comet assay detects DNA strand breaks induced directly by genotoxic agents as well as DNA degradation due to cell death. For this reason a contribution of toxicity in the observed effects was examined. We tested whether the exposed PBL were able to repair halothane- and isoflurane-induced DNA damage. The treated cells were incubated in a drug-free medium at 37 degrees C for 120 min to allow processing of the induced DNA damage. PBL exposed to isoflurane at 1 mM were able to complete repair within 60 min whereas for halothane a similar result was obtained at a concentration lower by one order of magnitude: the cells exposed to halothane at 1 mM removed the damage within 120 min only partly. We conclude that the increase of DNA migration induced in PBL by isoflurane at 1 mM and by halothane at 0.1 mM was not a result of cell death-associated DNA degradation but was caused by genotoxic action of the drugs. The DNA damage detected after the exposure to halothane at 1 mM was in part a result of DNA fragmentation due to cell death.

MeSH terms

  • Adult
  • Anesthetics, Inhalation / toxicity*
  • DNA Damage*
  • Electrophoresis, Agar Gel / methods
  • Halothane / toxicity*
  • Humans
  • In Vitro Techniques
  • Isoflurane / toxicity*
  • Lymphocytes / drug effects*
  • Male
  • Mutagens / toxicity*


  • Anesthetics, Inhalation
  • Mutagens
  • Isoflurane
  • Halothane