Inert gases such as argon, krypton, neon, and helium have no effect on N-methyl-d-aspatate (NMDA) receptors and TREK-1 channels. (A) Argon (80%) has no effect on NMDA-activated currents at high glycine (100 µm) and low glycine (1 µm) concentrations. Traces show typical currents activated by 100 µm NMDA in HEK cells expressing NMDA receptors containing the GluN1/GluN2A subunit combination. (B) NMDA receptor currents were unaffected by 80% argon (cyan bars), 80% krypton (brown bars), 80% neon (green bars), or 80% helium (black bars). The error bars are standard errors (100 µm glycine: argon N = 10, krypton N = 9, neon N = 5, helium N = 9; 1 µm glycine: argon N = 12, krypton N = 9, neon N = 6, helium N = 6). (C–F) Inert gases argon (80%), krypton (80%), neon (80%), and helium (80%) have no effect on TREK-1 potassium channel currents. (G) Xenon (80%) activates TREK-1 potassium channel currents. Data were sampled at 20 kHz and each trace contains 3,000 data points, lines shown are through these individual points. (H) Xenon (red bar) potentiates TREK-1 currents by 39 ± 5%, whereas argon (cyan bar), krypton (brown bar), neon (green bar), and helium (black bar) do not potentiate TREK-1 currents, measured at −50 mV. The error bars are standard errors and where not shown they are smaller than the bar (xenon, N = 5; argon, N = 3; krypton, N = 9; neon, N = 4; helium, N = 3).