Could radical pairs play a role in xenon-induced general anesthesia?

Abstract

Understanding the mechanisms underlying anesthesia would be a key step towards understanding consciousness. The process of xenon-induced general anesthesia has been shown to involve electron transfer, and the potency of xenon as a general anesthetic exhibits isotopic dependence. We propose that these observations can be explained by a mechanism in which the xenon nuclear spin influences the recombination dynamics of a naturally occurring radical pair of electrons. We develop a simple model inspired by the body of work on the radical-pair mechanism in cryptochrome in the context of avian magnetoreception, and we show that our model can reproduce the observed isotopic dependence of the general anesthetic potency of xenon in mice. Our results are consistent with the idea that radical pairs of electrons with entangled spins could be important for consciousness.

Entangled radicals may explain lithium effects on hyperactivity

“…In summary, our results suggest that quantum entanglement might lie behind the mechanism of lithium treatment for BD, similarly to magnetoreception in animals 33 and (as recently proposed) xenon-induced anesthesia 35 .…”

“…In this highly speculative context, entangled RPs could play crucial roles as sources of entanglement, and the present work could be viewed as another piece of evidence consistent with this idea in addition to Ref. 35 . In particular, superoxide radicals can give rise to singlet oxygen, which can emit photons 90 .…”

“…For example, it has also been proposed that Li could exert its effects on BD via increasing glutamate re-uptake at the N-methyl-D-aspartate (NMDA) receptor 64 . Inspired by the RPM's potential role in xenon-induced anesthesia 35 , where there the NMDA receptor has been proposed as the target site of xenon, a similar scenario could be envisioned here. For example, oxygen might oxidize Trp in the NMDA receptor and result in the formation of [TrpH -...O -2 ] RPs, and lithium might modulate the S-T interconversion of the RPs by coupling to the unpaired electron of O -2 .…”

“…The application of RPM has begun to gain momentum in numerous fields of research 34 . Most recently, Smith et al, inspired by the the RPM explanation of avian magnetoreception, have shown that the RPM could play a role in xenon-induced anesthesia, which exhibits isotopic dependence 35 .…”