HALOTHANE INDUCED CHROMOSOME ABERRATION OF HUMAN LYMPHOCYTE
Human lymphocytes obtained from healthy volunteer were cultured in Eagle's minimal essential medium equilibrated with various concentrations of halothane balanced with air for 48 hours and changes of their chromosomes were observed. Aberration rate of chromosomes of the lymphocytes exposed to 1 % halothane was increased significantly (<0.01). Aberration rate with 0.5 % halothane exposure tended to be slightly higher than that with air exposure while rates with other lower concentrations of halothane were quite identical with that in air exposure. Secondarily four gas mixtures were tested to observe additive effect of nitrous oxide. Namely (1) 1 % halothane + 74 % nitrous oxide + 25 % oxygen, (2) 75 % nitrous oxide + 25 % oxygen, (3) 1 % halothane + air, (4) air alone were tested. Consequently no aggravating effect of nitrous oxide on the aberration rate was demonstrated. Thirdly to determine the phase of cell cycle in which the aberrations would be induced, lymphocytes were divided into two groups. One of them was exposed to 1 % halothane for 24 hours at first and then to air for the second 24 hours. The other group was exposed to air first and then to 1 % halothane. Aberrations of the both groups were mostly identical and 87.5 % of these was classified into chromatid type and only 12.5 % into chromosomal type. It was indicated that halothane could cause changes in chromosomes mostly in the S phase, namely DNA synthesis period.