N. Kuratani et al., MULTIPLE BUT DIFFERENT GENETIC-FACTORS UNDERLIE ENFLURANE AND ISOFLURANE REQUIREMENTS STUDIED THROUGH BACKCROSS ANALYSIS IN C57BL AND DDN MICE, Anesthesia and analgesia, 83(4), 1996, pp. 798-803
We performed a classic backcross analysis to examine the basic genetic
nature of enflurane (ENF) and isoflurane (ISO) anesthetic requirement
in two inbred mice strains, C57BL (BL) and ddN. We have previously re
ported different ENF and ISO anesthetic requirements in these two stra
ins. BL (n = 22) and ddN (n = 26) mice were used as parents and were r
eciprocally crossed to produce F1 hybrid mice. Each F1 offspring was c
rossed to its parent to produce backcross siblings (BF1). Anesthetic e
nd point was determined as the loss of righting reflex. Measurement of
anesthetic requirement was performed during 8-12 wk after birth. Alth
ough ddN mice showed slightly less resistance to ENF and ISO compared
with our previous report, they were more resistant than BL mice. Multi
variate regression analysis of parents' and F1 hybrids' data revealed
that, while maternal factors and factors on autosomes were related to
both anesthetics, the factors on the X chromosome were ENF specific. A
wide variation in anesthetic requirements among BF1 progeny suggested
multifactorial inheritance. The regression equations obtained did not
always predict anesthetic requirement in BF1 progeny. These discrepan
cies may be due to the epistatic interaction of related genes. We conc
lude that multiple but different genetic factors are involved in deter
mining ENF and ISO anesthetic requirements in BL and ddN mice.