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Comment by IsTom | Hacker News Reader

Wouldn't it be the same as breathing any other nonreactive gas? Isn't this just symptoms of hypoxia?

No, xenon is a NMDA antagonist meaning it has dissociative/anaesthetic effects like ketamine or nitrous oxide.

TFA talks about the effects coming on "within seconds" of inhalation, so it is clearly not just hypoxia which takes tens of seconds or minutes to manifest.

How does it do that without forming chemical compounds? Is it like a catalyst for another reaction or something?

Even though xenon doesn't easily form "compounds" in the normal chemical sense, it does weakly interact with other molecules through van der Waals forces, which are strong enough to affect the functioning of various receptors in neurons.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467505/

I'm not an expert on the biochemistry, but Wikipedia has a summary of some of the known interactions at:

https://en.wikipedia.org/wiki/Xenon#Anesthesia

It will still react through (weaker) non covalent forces, like van der Waals force.

Reactions don't need to happen, the magnesium ion is a single atom that interacts with the NMDA receptor to block it at specific potentials. When the postsynaptic neuron gets enough input at a synapse, there is enough change in the charge inside the cell where it allows the Mg2+ ion to be displaced from the pore to allow cations to pass through

Our cells use single atoms, usually in the form of charged ions, on a regular basis and we would not survive without them

But wouldn't xenon (as a noble gas) be pretty hard to ionize? Without a charge it shouldn't interact the way ions do.

Charge is not the only way that molecules interact

https://en.m.wikipedia.org/wiki/Van_der_Waals_force

I'm not very knowledgeable on this, but my understanding is that xenon can dissolve in the lipids in the brain and influence reactions in that state. This paper [1] seems to show that xenon can displace glycene in the NMDA receptors. The receptor is a "door" and glycene is one of the "keys" to open. By binding or interacting with the glycene site on the receptor, xenon keeps glycene from reaching the receptor, inhibiting it.

[1] https://pubs.asahq.org/anesthesiology/article/112/3/614/1084...

Asphyxiation with inert gases causes hypoxia very quickly. It's not like holding your breath. Lungs don't actively pump oxygen; gases just diffuse along their partial pressure gradients. Air has higher partial pressure of oxygen than blood does, so the oxygen diffuses from the air to the blood. If you fill the lungs with inert gas the oxygen diffuses back out again. You're effectively breathing in reverse.

Filling the lungs with vacuum has the same effect. You have about 5 to 10 seconds before you're incapacitated:

https://en.wikipedia.org/wiki/Time_of_useful_consciousness

Either way, it has been known for a while that xenon is an NMDA antagonist (hypoxia aside).

And, importantly, it's always mixed with oxygen when used that way.

Clearly the symptoms aren't the same as just holding your breath, which makes me think that it is not, in fact, completely nonreactive. (But I'm a total noob to biochemistry.) Similar to Nitrous Oxide, which definitely has a powerful psychedelic effect and is not at all simply hypoxia.

I wouldn’t call nitrous oxide “psychedelic” although it is certainly psychoactive.

It depends on your definition of psychedelic then, as I find different sources supporting either argument, but NO2 produces powerful hallucinations, euphoria, dissociation, and sometimes creativity much like typical psychedelics, but on a compressed timescale.

Many people also consider ketamine a psychedelic and the primary mechanism of action is NMDA antagonism preferring the NR2B subunit

It's common to distinguish between "psychedelics", which primarily function via serotonin receptors, and "dissociatives", which primarily function via NMDA receptors.

The term psychedelic is describing specific subjective effects rather than a mechanism of action, what you're thinking of are the classic serotonergic psychedelics which are 5ht2a agonists but ketamine and other dissociatives can be considered dissociative psychedelics

Not really. Cannabis and salvinorins are commonly used for psychedelic effects. Many psychedelic compounds cause dissociation, e.g. LSD.

I’ve heard that Ketamine is a psychedelic deepener more than a psychedelic on its own. Ie, a little ket addition is similar to taking a much higher dose of psychedelics (but short duration): high definition mental imagery and expanded external visual effects. With a good set & setting, that combo nearly guarantees a mystical experience.

A compound that can deepen a psychedelic experience can also be a psychedelic on its own. There are people who like to smoke DMT during the peak of an LSD experience because of this deepening but both are capable of producing mystical experience on their own, just as ketamine (especially the S isomer) is capable of

As someone who had it during surgery... it's 100% psychedelic at sufficient dose.

Hallucinations on N2O? How long do you have to breath it for that?

Not very long necessarily. You just need to be primed

it sure does make other psychedelics a lot lot lot more intense though

Xenon gas is nonreactive, but it can dissolve into your blood and influence the very sensitive chemistry of your brain.

React is not a good term to use here but rather interact. Saying something reacts means that we are moving around electrons and possibly forming covalent or ionic bonds. Intermolecular interactions are quite a bit different

Or displace, in this case exotic xenon for ambient argon and nitrogen.

Argon is basically a rounding error in atmospheric gases.

Xenon has been the gas anesthetic of the future for a long time now. It does have one set of good qualities: it's not halogenated (like all common gas anesthetics), but it's nonflammable (there are very good anesthetic gases, like cyclopropane, that are extremely flammable and have thus been totally phased out of use), and because it's such a heavy atom, it essentially never leaves the atmosphere - no matter how much you use, you can always recapture it from the atmosphere.

It's not particularly cheap, though.

Much higher quality comment than mine above.

I suppose from the article that a dose of Xenon is $300 of gas, of which $50-$80 is not immediately reclaimed by a rebreather.

I'm fairly certain when administered medically it's a controlled mix of oxygen and xenon, like nitrous at the dentist. They're not asphyxiating you, these molecules are psychoactive.

You're supposed to breath it mixed with oxygen.

I do the Wim Hof breathing exercise that involves up to 15 seconds of hypoxia. I get a pretty significant head change from it. Hopefully I’m not causing any permanent damage.

Yeah, how can the body tell which noble gas it's breathing? As the article mentions, the xenon is exhaled in its original form without having been metabolized or having caused any chemical changes in the body!

Chemistry is a subset of physics, not the other way around.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10218445/

Different atoms have different sizes and if you look into how ion channels work you can see that there are many processes in biochemistry that are incredibly specific to size and charge

> having caused any chemical changes in the body

But it does cause chemical chsnges. Noble gasses can weakly interact. It does not need to form bonds to influence potential gradients, protein shapes, or other reactions.

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