Fig. 2. Xenon exerts a concentration-dependent neuroprotective effect in vitro . Neuronal cultures were treated with either (A ) 250 μm NMDA or (B ) 100 μm glutamate for 10 min in the presence of increasing concentrations of xenon. The xenon IC⁵⁰concentrations for neuroprotection were 19 ± 6 and 28 ± 8% for NMDA and glutamate-induced injury, respectively (mean ± SEM). (C ) Xenon was also neuroprotective in cultures deprived of oxygen (circles) for 75 min before rescue with medium containing 20% oxygen. In all cases, neuronal injury is expressed as a percentage of the maximum lactate dehydrogenase (LDH) release after 6 h determined in the absence of xenon. The points represent mean ± SEM (n = 3).