Effect of general anaesthetics on synaptic ion channels.

General anaesthetics are a large group of physiologically active substances which, although structurally diverse, are generally regarded as possessing one common physical-chemical property—a high solubility in hydrophobic solvents. Clinically, general anaesthetics have the well known and very useful properties of being able to abolish sensation and to produce unconsciousness, and are thus used to control pain. Although the state of anaesthesia is not yet adequately understood, it can be viewed as a suspension of some of the normal key functions of the central nervous system which is reversible as long as the dose of the anaesthetic given is carefully controlled. This review is concerned with the mechanism of action of general anaesthetics at a synaptic level and particular attention will be paid to the action of general anaesthetics on the postsynaptic membrane. Unfortunately we cannot hope to explain the mechanism of general anaesthesia itself simply by studying the actions of general anaesthetics at a synaptic membrane level. We do not, for example, even know exactly where in the brain consciousness is controlled. However, a knowledge of the mode of action of these agents is an aid to being able to control their effects and to improve the use of such drugs in clinical medicine. Ultimately we must hope that the gap between the membrane and molecular approach to anaesthetic action and the way in which general anaesthetics produce anaesthesia will narrow and eventually disappear.