Cross-mating of mice selectively bred for resistance or susceptibility to nitrous oxide anesthesia: potencies of nitrous oxide in offspring.

To investigate the genetic bases of differences in nitrous oxide requirement in mice selectively bred for resistance (HI mice) or susceptibility (LO mice) to nitrous oxide anesthesia, the potency of nitrous oxide in offspring having one HI and one LO parent was measured. Nitrous oxide ED50S (+/- SD) in offspring having HI male and LO female parents or LO male and HI female parents were 1.53 +/- 0.10 and 1.63 +/- 0.14 atm, respectively. In contrast, the nitrous oxide ED50 for offspring having two LO parents was 1.26 +/- 0.09 atm, and for offspring having two HI parents, 1.96 +/- 0.10 atm. Thus, the nitrous oxide ED50S for offspring produced by cross-mating HI and LO animals approximated the average values for their parents. We conclude that no single one gene determines dominance or recessiveness for nitrous oxide requirement in mice, and that the genetic control of resistance or susceptibility to nitrous oxide anesthesia probably involves many genes.