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 Ž .
migration in a dose-dependent manner. In experiments conducted at two different electrophoretic conditions 0.56 and 0.78 Ž
Vrcm , 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 378C 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