Fig. 3. ( A ) Glycine concentration–response curve for activation of NR1/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 8 cells. The error bars are SEs; where not shown, these are smaller than the symbol. ( B ) Xenon (80%) inhibition of NR1/NR2A receptors increases as glycine concentration is reduced. ( C ). Inhibition of NR1/NR2A receptors by 0.3 mm (1 minimum alveolar concentration [MAC]) isoflurane ( black bars ) and 1.2 mm (4 MAC) isoflurane ( cross-hatched bars ) increases as glycine concentration is reduced. The bars represent mean values from an average of 8 cells (xenon) or 7 cells (isoflurane) at each glycine concentration. The error bars are SEs. * Significantly different ( P < 0.05) from control (100%), indicated by dashed line .