Strain-differences of sensitivity to volatile anesthetics and their genetic character in mice.

Using loss of the righting reflex, we determined the ED50 values for enflurane, isoflurane, sevoflurane and halothane in white-haired ddN mice and black-haired C57BL mice. The ED50s (Mean +/- SEM) in ddN and C57BL mice for enflurane were 1.65 +/- 0.01 and 1.19 +/- 0.01% atm, for isoflurane 1.02 +/- 0.01 and 0.74 +/- 0.01% atm, for sevoflurane 2.29 +/- 0.03 and 1.95 +/- 0.03% atm, and for halothane 0.97 +/- 0.01 and 0.97 +/- 0.01% atm, respectively. The results indicate that the ddN strain is more resistant to enflurane, isoflurane and sevoflurane than the C57BL strain. The sensitivities to enflurane and isoflurane is F1 progeny of reciprocal crosses between ddN and C57BL mice revealed that in the ddN strain enflurane resistance is an incompletely dominant or polygenic character, isoflurane resistance in ddN strain is an autosomal recessive character and both are controlled by genes on the sex (X) chromosome. Enflurane and isoflurane resistances are controlled by at least 2 genes, one on the X chromosome, and each resistance is controlled by a different genetic mode