Talk:Outdated theories of anaesthetic action
From Wikipedia, the free encyclopedia
Ralf Schmelter 21:45, 2004 Nov 16 (MET)
As far as I know, the difference of the anaesthetic potency of chiral molecules is rather small (as far as I remember usually a few 10 percent, at most a factor of 2) and only seen for some chiral anesthetics. So it's by far smaller than usually seen in biologically active chiral molecules (think of thalidomide for example). So the small difference in anaesthetic potenciy of some chiral molecules are by no means a strong indication for a direct interaction between the anaesthetic and protein (by the way, the lipids itself are, despite what the article say, chiral because of the chiral carbon atom of the glycerol backbone).
The cutoff-effect mentioned, which, according to this article, is 'easily' explained by a hydrophic pocket of a fixed size, is found for many different homologeous series of chemical compounds. For example for 1-alcoholes, a cutoff of about n=12 (n is the number of carbon atoms) is found, while for perflouroalkanes the cutoff is at n=2. Clearly, this is not an evidence for that propoped hydrophobic pocket.
As far as I can see, there is currently no theory which can accommodate all the various findings about the anaesthetic potency of various chemical compounds (see e.g. the vast amount of data by Eger et.al). The only thing which seems to be clear, is that the in the end the ligand-gated ion channels are the target of the anesthetics. But if they interact directly with these ion channels or the effect is indirect (e.g. as Cantor suggest, that the anesthetics change the lateral pressure profile of the membrane and therefore change the free energe difference between the open and closed state of the ion channel) remains unclear. The main problem for a theory seems to be, to incorporate the findings from such simple 'molecules' as argon to complex halogenated molecules. The theories I know are currently know, are only able to explain some of the findings, while others remained unexplained or are in contradiction to the theory. So I would not rule out the lipid-based theories (apart from the very simple ones).
[edit] Combine this with General anaesthetic ?
Does it really make sense to have this page stand by itself separate from another more comprehensive article like General anaesthetic? It is rather weak out of context. --Oasisbob 10:33, 1 December 2005 (UTC)
