Nitrous oxide, xenon, and cyclopropane are anesthetic gases that have a distinct pharmacological profile. Whereas the molecular basis for their anesthetic actions remains unclear, they behave very differently to most other general anesthetics in that they have little or no effect on GABA A receptors, yet strongly inhibit the N-methyl-D-aspartate subtype of glutamate receptors. Here we show that certain members of the two-poredomain

Properties, kinetics and functions of large conductance calcium‐activated K+ channels (BKCa) were investigated by the patch‐clamp technique in small neurones (Aδ‐ and C‐type) of a dorsal root ganglion (DRG) thin slice preparation without enzymatic treatment. Unitary conductance of BKCa channels measured in symmetrical high K+ solutions (155 mm) was 200 pS for inward currents, and chord conductance in control solution was 72 pS. Potentials of half‐maximum activation (V1/2) of the channels were linearly shifted by 43 mV per log10[Ca2+]i unit (pCa) in the range of −28 mV (pCa 4) to +100 mV (pCa 7). Open probabilities increased e‐times per 15–32 mV depolarization of potential. In mean open probability, fast changes with time were mainly observed at pCa > 6 and at potentials > +20 mV, without obvious changes in the experimental conditions. BKCa channels were half‐maximally blocked by 0.4 mm TEA, measured by apparent amplitude reductions. They were completely blocked by 100 nm charybdotoxin and 50 nm iberiotoxin by reduction of open probability. Two subtypes of small DRG neurones could be distinguished by the presence (type I) or absence (type II) of BKCa channels. In addition, less than 10 % of small neurones showed fast (∼135 V s−1) and short (∼0.8 ms) action potentials (AP). The main functions of BKCa channels were found to be shortening of AP duration, increasing of the speed of repolarization and contribution to the fast after‐hyperpolarization. As a consequence, BKCa channels may reduce the amount of calcium entering a neurone during an AP. BKCa channel currents suppressed a subsequent AP and prolonged the refractory period, which might lead to a reduced repetitive activity. We suggest that the BKCa current is a possible mechanism of the reported conduction failure during repetitive stimulation in DRG neurones.

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Objectives-To determine the neuroprotective efficacy of the inert gas xenon following traumatic brain injury, and to determine whether application of xenon has a clinically relevant therapeutic time window.Design-Controlled animal study. Setting-University research laboratory. Subjects-Male C57BL/6N mice (n=196)Interventions-75% xenon, 50% xenon or 30% xenon, with 25% oxygen (balance nitrogen) treatment following mechanical brain lesion by controlled cortical impact.Measurements & Main Results-Outcome following trauma was measured using: 1) functional neurological outcome score, 2) histological measurement of contusion volume, 3) analysis of locomotor function and gait. Our study shows that xenon-treatment improves outcome following traumatic brain injury. Neurological outcome scores were significantly (p<0.05) better

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