The Role Of Nuclear Spin In Xenon Isotopes Anesthetic Potency And Its Relationship With Consciousness

Part1.Measurement of the anesthetic potency of xenon isotopesObject:Xenon is a monoatomic anesthetic with nine stable isotopes.According to nuclear spin,nine xenon isotopes can be divided into three types:xenon 131(¹³¹Xe)with nuclear spin of 3/2,xenon 129(¹²⁹Xe)with nuclear spin of 1/2,and the other isotopes with zero nuclear spin.Anesthesia is the opposite of consciousness.Xenon,as an inert anesthetic gas,does not participate in chemical reactions in the brain(except for extreme conditions),and its nuclear spin(nuclear spin is a typical quantum feature)is abundant in species.Xe is a good tool to explore the relationship between quantum and consciousness.This part was aimed to explore the anesthetic potency of ¹²⁹Xe,¹³¹Xe,¹³²Xe and ¹³⁴Xe.Methods:According to the random number table generated by Excel software,eighty C57BL/6 mice were randomly divided into four groups,which were xenon 132(¹³²Xe),xenon134(¹³⁴Xe),¹³¹Xe and ¹²⁹Xe groups,respectively,20 mice per group.Due to the low potency of xenon,and the additive of xenon and isoflurane on hypnosis,loss of righting reflex ED50for mice to xenon was determined with constant 0.50%isoflurane.After mice rested for 4days,loss of righting reflex ED50 of isoflurane was also measured.According to the contribution of isoflurane in the normalized combined ED50 values for both isoflurane and xe,the anesthetic potency of xenon isotopes was then calculated.Results:1.Combined with constant 0.50%isoflurane,the loss of righting reflex ED50 values of mice were 15±4%(Mean±SD,95%CI,15 to 17%),16±5%(95%CI,14 to 16%),22±5% (95%CI,21 to 22%)and 23±7%(95%CI,22 to 24%)for ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe, respectively.2.The loss of righting reflex ED50 values of mice in ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe group were 0.65±0.02%,0.64±0.04%,0.64±0.03%and 0.65±0.03%,respectively.There was no significant difference in ED50 values among four groups.The loss of righting reflex ED50 for the same mice to isoflurane was 0.64±0.01%(95%CI,0.64 to 0.65%) after fitted with dose-response curves.3.For xenon alone,the loss of righting reflex ED50 values of ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe were 71±4%(95%CI,70 to 72%),72±5%(95%CI,71 to 73%),99±5%(95%CI,96 to 99%)and 105±7%(95%CI,104 to 106%)in mice,respectively.Conclusions:The anesthetic potency of xenon isotopes was measured by loss of righting reflex.It was found that xenon isotopes with nuclear spin(¹³¹Xe and ¹²⁹Xe)have less potent than those without(¹³²Xe and ¹³⁴Xe).¹²⁹Xe with nuclear spin of 1/2 has the lowest anesthetic potency.There was no statistical difference in anesthetic potency between the two xenon isotopes with zero nuclear spin.Mass differences and chemical properties of xenon isotopes cannot explain the difference in anesthetic potency of xenon isotopes.Part2.Effect of polarizability on anesthetic potency of xenon isotopesObjects: Current research shows xenon binding to proteins was mainly through van de Waals force,thus exerting its anesthetic effect.Van der Waals force of non-polar molecule xenon is mainly induced dipole-dipole force and fluctuating dipole-induced dipole force.Induced dipole-dipole force is related to polarizability,and fluctuating dipole-induced dipole force is related to polarizability,molecular size and shape.Polarizability is the degree to which a molecule can be instantaneously polarized by nearby charge distributions.The polarizability of anesthetics correlates with its anesthetic potency.The higher the polarization is;the stronger anesthetic potency is.Xenon has a quite high polarizability.In this part,the influence of polarizability and van der Waals force on the anesthetic potency of xenon isotope is analyzed by calculating the polarizability of xenon isotopes ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe.Methods: Quantum chemical calculation of the exact polarizability of ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe was performed by using Gaussian view 6.0 and Gaussian 09 software with the density functional theory method and B3LYP/3-21 G.Results: Four isotopes ¹³²Xe,¹³⁴Xe,¹³¹Xe and C had a same exact polarizability of 3.60?³.Conclusions: The exact polarizabilities of four xenon isotopes ¹³²Xe,¹³⁴Xe,¹³¹Xe and ¹²⁹Xe were the same.Now molecular size and shape of these four isotopes were the same,so polarizability and van der Waals force cannot give rise to the difference in anesthetic potency among the xenon isotopes,the explanation of the difference in anesthetic potency among them may be in the atomic nucleus.The lower anesthetic potency of ¹²⁹Xe may be the result of it participating in conscious processing and therefore partially antagonizing its own anesthetic potency,due to the quantum property of nuclear spin,and our results were consistent with theories that implicate quantum mechanisms in consciousness.