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What you are all refering to is the "critical volume hypothesis" as proposed by (sorry the name slips my mind). What this theory and it's variations state is that anaesthesia occurs by the anaesthetic gas dissolving into the lipid membrane. Now the interesting thing is that increased pressure reverses the effects of anaesthesia. These experiments were done on tadpoles, which when anaesthetised turn on their side, when placed under pressure they return to normal swimming. What was thought to be happening is that as the anaesthetic gas dissolves in the membrane in increases in size so affecting ion channel conductance and possible receptor binding. The pressure reverses the increase in size. The correlation between anaesthetic potency and lipid solubilty was found to be closely related (at least for those gases that were anaesthetics). How does all this relate to diving. As the pp nitrogen goes up then more will dissolve into the lipids and for the other narcotic gases as well. The bad news is that this theory is pretty much has been disproved. One good question to ask about it is, if narcosis has to do with lipid solubilty alone, and that solubility has to be governed by Henry's Law then why does it occur almost immediately on reaching the depth and also recover alomost immediately when removed from that depth. Surely there ought to be a time lag to allow the gas to dissolve and have its effect and for it to be off gassed on ascent. John Gibbons School of Pharmacy London PS I need to find a good source of CO2 absorbent in cartridge form any help would be appreciated
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