Neurological Theories of Action
The full mechanism of action of volatile anaesthetic agents is unknown and has been the subject of intense debate. "Anesthetics have been used for 160 years, and how they work is one of the great mysteries of neuroscience," says anaesthesiologist James Sonner of the University of California, San Francisco. Anaesthesia research "has been for a long time a science of untestable hypotheses," notes Neil L. Harrison of Cornell University.
"Most of the injectable anesthetics appear to act on a single molecular target," says Sonner. "It looks like inhaled anesthetics act on multiple molecular targets. That makes it a more difficult problem to pick apart."
The possibility of anaesthesia by the inert gas argon in particular (even at 10 to 15 bar) suggests that the mechanism of action of volatile anaesthetics is an effect best described by physical chemistry, and not a chemical bonding action. However, the agent may bind to a receptor with a weak interaction . A physical interaction such as swelling of nerve cell membranes from gas solution in the lipid bilayer may be operative. Notably, the gases hydrogen, helium, and neon have not been found to have anaesthetic properties at any pressure. Helium at high pressures produces nervous irritation ("anti-anaesthesia"), suggesting that the anaesthetic mechanism(s) may be operated in reverse by this gas (i.e., nerve membrane compression). Also, some halogenated ethers (such as flurothyl) also possess this "anti-anaesthetic" effect, providing further evidence for this theory.
Read more about this topic: Inhalational Anaesthetic
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