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Isn't the issue actually one of the effect of either nitrogen or oxygen's effects on the synaptic pathways? If nitrogen's effects are generated by loading into lipid structures, namely myelin tissues, oxygen loading may have a very different mechanism (and outcomes). At 4/27/97 3:33 PM -0500, <CHKBOONE@ao*.co*> wrote--------: >Phil, John, > > Well I have read over the archives on this subject as a start and >it appears that everyone is up in the air about it. Many and varied >thoughts on the actual causes of the reported effects that Richard >Pyle observed under conditions so far removed from reasonable >exposures as to fall into the realm of reason concurrent with the >experience that too much of anything is poisonous or narcotic. > There were ideas about consequential CO2 retention due to so >much O2 in solution that seem reasonable to consider at first >glance. > > >---------------------------- >Phil wrote in e-mail : > >>. . . . Many believe, narcosis (note, I have not said >>"nitrogen narcosis" or even "inert gas narcosis") is not due solely >>to the effects of increased nitrogen partial pressure. If, as I >>originally stated, oxygen has a similar (or greater) narcotic >>potential to nitrogen, then EANX will have an equal (or greater) >>narcotic effect to air. > >>For the time being (and unless you can provide scientific evidence >>to convince me otherwise), I prefer to believe that oxygen has a >>narcotic potential equal to or greater than that of nitrogen. >>Therefore, I hold to my original OPINION that breathing nitrox >>confers no narcosis reduction. . . . . > > >---------------------------------------- >John Strohm wrote in e-mail : > >>As I understand it: The current theory says that the narcotic potential o= f >>a gas, any gas, is related to its lipid solubility. > >.. . . . and the molecular or atomic weight of the gas. > >>This theory, IF CORRECT, would predict that oxygen would have just >>about the same narcotic potential as nitrogen, because they have similar >>lipid solubilities. . . . . . . FURTHERMORE, it would predict that nitr= ox > >>would show no benefit over air for narcosis, because there would not be >>any significant difference in narcotic potentials. > >>Trout's take on it, which he related to us in the class, is that nitrox, I= N >>HIS PERSONAL EXPERIENCE, causes significantly less narcosis than >>air, which>is NOT what the theory predicts. He didn't have an explanation >>for thedifference. > > >But, gentlemen, EANx as commonly used does =EBnot=ED have an equal or >greater narcotic effect than air in spite of the elevated PPO2. I believ= e >it is safe to state that divers commonly experience less narcosis with >reduced PPN2 in spite of elevated PPO2 on the other side of the >equation. Nitrox ! > >Allow me to offer you both an explanation as to why nitrox reduces >narcosis in spite of elevated O2. This is my own theory - not gospel, >but I think it fits the observations well. > > Oxygen is metabolically active suggesting that the only oxygen available >to operate under the dictates of this theory is what goes into solution in >the >plasma and tissues (not bound to hemoglobin). There is enough >hemoglobin in the blood to hold much more O2 than it carries during normal >activity so a tremendous amount of the excess O2 in nitrox will bind with >hemoglobin leaving little left to go into solution in the plasma and tissue= s >causing narcotic effects. If enough O2 remains bound with hemoglobin as >it passes through the tissues it will restrict the elimination of CO2 - O2 >toxicity. >You will likely reach the threat of O2 tox before there is enough O2 in >solution >in the plasma and tissues to cause narcosis. This goes along with the >observed results which are that CNS limits you before narcotic effects do. > >So even though there is more O2 in your mix it is not doing the same thing >that the N2 is in the body until there is so much of it that the hemoglobin >is >saturated and it begins to dissolve in the plasma and tissues when it might >very well cause narcotic effects. >This means that we get a grace period, shall I say, during which we can >increase the amount of O2 without it being deposited in the same manner >as inert gases are. > >So nitrox would have a lower narcotic effect at any depth than air because >there is less N2 going straight into solution and up to a point most or all >of the >increased O2 is captured by hemoglobin. Even before the hemoglobin is >saturated with oxygen CO2 elimination should become a problem. Lots of >O2 is beginning to dissolve into the plasma and tissues providing a reservo= ir > >of O2 to keep the hemoglobin saturated. Blood chemistry has changed, >CO2 is building up in the tissues, and you are well into O2 toxicity which >will >quite possibly kill you before you start to notice the narcotic effects of >the >dissolved oxygen. > >This slow dissolving of O2 into the tissues could be why narcosis gets wors= e >with time at depth in some cases. > >--------------------------------------------- >More interesting questions : > > Why, if elevated N2 has effects on the fatty myelin sheath, does it not >have >an effect at lower partial pressures? In other words if N2 is truly inert >in the >body why would more N2 suddenly become reactive with this tissue as it=EDs >partial pressure rises? >It would seem that there must be some action between N2 and this tissue >that is modified at higher partial pressures rather than being non existent >until >the N2 pressure is elevated. > > Is it possible that there is not enough O2 available to act >synergistically with >the N2 until it=EDs partial pressure forces enough into solution in the blo= od >plasma >(free of hemoglobin bond) ? > > Why, if these inert gases are not at the root of the narcotic effect, is >there >variation between the effects of Argon, Neon, and Nitrogen at the same >partial >pressures ? How can one be more narcotic than the other if the cause is >not in the properties of the inert gas itself ? > >Argon and Neon are chemically inert whereas Nitrogen is only physiologicall= y >inert. The significance of this is that if O2 plays a synergistic role >with N2 to >give the effects Pyle observed the same effects would probably not be >observed >with Argon or Neon. I would bet they would be, but by different >mechanisms. > > Oxygen is next to Nitrogen on the periodic table with atomic wts of 16 & >14 >respectively. O2 is slightly heavier than N2 but O2 is metabolically acti= ve >in >the body and everywhere else. Nitrogen has that =EC3=EE valence or oxidat= ion >state >that makes it almost inert in nature. It characteristically reacts with O= 2 >in >electrical discharges (fatty myelin sheath around nerve cell axons ???) > > >I have read an account of the effect nitrogen has on the nervous system tha= t >details the chemical reactions at the axons but can not remember where. > >Any pathologists out there ? > >Chuck >-- >Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. >Send list subscription requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send list subscription requests to `techdiver-request@aquanaut.com'.
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