Theories of general anaesthetic action

As Meyer- Overton correlation ( Meyer- Overton hypothesis, Meyer- Overton rule) the correlation of the effects of anesthetics with their lipid solubility ( lipophilicity ) is called. It was used a long time to explain the anesthetic effects, which is now regarded as largely obsolete.

Developing the theory

The pharmacologist Charles Ernest Overton in Zurich and Hans Horst Meyer in Marburg independently developed the hypothesis came from observations of anesthetics in tadpoles and the solubility of substances in olive oil:

" The relative potency of such narcotics must depend on their mechanical affinity for fat-like substances on the one hand to the other body components, di mainly water on the other; consequently of the Theilungskoeffizienten that determines their distribution in a mixture of water and fat-like substances. " (Meyer, 1899)

Subsequently, various lipid theories have been described from the context (also: lipoid theories ) of the anesthetic effect derived. This postulated that anesthetics act on the lipid bilayer of the cell membranes of nerve cells in the brain and have therefore fettlöslichere means a stronger effect. Various mechanisms, such as changes in flow characteristics or the permeability of the membranes have been discussed in the course of time. The lipid -based anesthetic theories dominated the most of the 20th century.

Today's meaning

Although it is also possible to describe the anesthetics used today, according to the Meyer- Overton correlation, can be theories about the mechanisms of action of anesthetics that are based on it, is no longer maintained. The idea of ​​a unified mechanism ( Unitaritäts principle) is now considered obsolete and replaced by the concept of multiple mechanisms and sites of action. Effects on a number of (protein -based ) receptors and ion channels ( opioid receptor, the GABAA receptor, NMDA receptor, sodium and potassium channels) and another modification of synaptic transmission in several areas of the central nervous system, which for some anesthetics exist in varying degrees of anesthesia be held responsible according to current knowledge on the various dimensions. A comprehensive anesthesia theory, which can be explained from the known mechanisms, but it is not available, so an effect according to the Meyer- Overton hypothesis ( impact on the lipid components of the central nervous system ) ultimately can not be excluded and will be discussed to some extent controversial.