Species variation and the mechanism of pressure–anaesthetic interactions


Play all audios:

The mechanism of general anaesthesia has proved difficult to elucidate (see ref. 1 for a review), although the relative potencies of anaesthetic agents have been used to establish that the


site at which anaesthetics act is hydrophobic in nature2. One further clue to their mode of action is that the effects of anaesthetics on vertebrates can be eliminated by pressures of ∼100


atm (refs 3, 4). However, the effects of anaesthetics are not always reversed in model systems, where there is evidence that the pattern of pressure reversal varies significantly5–10. We now


find that pressure fails to reverse the effects of anaesthetics on the freshwater shrimp (Gammarus pulex), although the sensitivity of these crustaceans to anaesthetics is comparable with


that of higher animals. This is hard to reconcile with traditional bio-physical mechanisms and indicates that anaesthetics may act at a specific protein site rather than having a general


effect on cell membranes. The pharmacology of pressure in mammals seems to be more similar to that of strychnine than of any other central stimulant11. As glycine, whose action is blocked by


strychnine, is absent as a neurotransmitter in the arthropod central nervous system, we believe that this substance may be involved in determining pressure–anaesthetic interactions in


vertebrates.


W. D. M. Paton: Department of Pharmacology, South Parks Road, Oxford OX1 3QT, UK


Physical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, UK


E. B. Smith, F. Bowser-Riley, S. Daniels, I. T. Dunbar, C. B. Harrison & W. D. M. Paton


Anyone you share the following link with will be able to read this content: