Fig. 6. (  A ) Glycine concentration–response curve for activation of mutant NR1(F639A)/NR2A receptors at a concentration of 100 μm  N -methyl-d-aspartate. The curve is fitted to the Hill equation. The  points represent mean values from an average of 6 cells at each concentration. For comparison, the glycine concentration–response curve for the wild-type NR1/NR2A receptors (NR1wt) is shown in  gray . (  B ) At a glycine concentration of 1 μm, the wild-type receptors are inhibited at 1 minimum alveolar concentration (MAC) (  black bar ) and 4 MAC (  white bar ) isoflurane, respectively. At 1 μm glycine, the NR1(F639A)/NR2A receptors are less sensitive to 1 MAC isoflurane (  gray bar ) and 4 MAC isoflurane (  cross-hatched gray bar ). Isoflurane inhibition of NR1(F639A)/NR2A receptors is restored at a 0.03 μm glycine. (  C ) At a glycine concentration of 1 μm, xenon (80%) inhibits the wild-type receptors (  white bar ). At 1 μm glycine, the NR1(F639A)/NR2A receptors are less sensitive to 80% xenon (  gray bar ). Xenon (80%) inhibition (  gray bar ) of NR1(F639A)/NR2A receptors increases at 0.03 μm glycine. The  bars are means for an average of 6 cells at each concentration.  Error bars are SEs. * Significantly different (  P < 0.05) from control (100%), indicated by  dashed line .