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To add a little more to this discussion on lipids... The concept of general anesthesia is an interesting one, as it appears to affect ALL cells. A physical chemist I know thought that the phenonmon was unusual and went to study the PHYSICS of the problem. He found that for halothane (one of the most common anestheics, the?), halothane dissolved in the lipid layer of the cell membrane and caused it to melt. Under normal physiological conditions, the lipids are (mostly) crystaline in structure. Unlike many structural studies of anesthetics, this was determined using raman spectroscopy of the actual lipid in a living cell. (N.C. Craig, etal. JACS, 1979...) The hypothesis from this was that the melted lipid layers crushed or otherwise denied support for critical transmembrane processes such as O2, sugar, waste transport. It is also known that some gases (Xe, O2) have been found to intercalate into proteins-but normally without distorting their structure. The gasses that intercalate best seem to have either a small size (e.g. He) or a polarizable outer shell of electrons (Xe or Nitrous Oxide). The latter gases are also highly soluble in lipids, nitrous oxide being used in the explosive decompression of cream to make 'whipped' topping. (Is that why one feels whipped after a dive? :-) ... ) Obviously, there are many gases and other substances that could cause a similar effect. Prime rat and others could comment on the specific nature of oxygen toxicity, in contrast to some of the more general effects of narcosis. Many of these effects may be biological and chemical in nature. i.e. High pressure N2 binding in place of NO on neural receptors. I hope this helps understand some of the physical processes going on. Safe diving, Peter David
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