Receptor general anaesthetics

In the literature, one can find many more interesting MD studies concerning lipid bilayers with additives. In particular, a wealth of MD simulations of such systems is in the field of anaesthetics (for a review see [142]). Many anaesthetics tend to accumulate at the membrane/water interface, implying that their potencies are not related to their ability to cross the membrane. Instead, it seems to be more likely that their functioning is via binding to membrane receptors. Generally, they have an effect opposite to that of cholesterol, i.e. they increase the membrane fluidity and permeability. 

Carla V, Moroni F. 1992. General anaesthetics inhibit the responses induced by glutamate receptor agonists in the mouse cortex. Neurosci Lett 146(l) 21-24. 

Atropine blocks muscaric cholinergic receptor competitively and has a large spectrum of clinic applications. Atropine acts as a parasympatholytic on parasym-phathetically innervated organs. Therefore, the possible applications of atropine are as a general anaesthetic and include its use in pure form or as a component. 

Recent research has indicated select abnormalities in the cholinergic system (Perry et al., 2001). Although previously unexamined neurochemically, there was an indication that the cholinergic system may be involved in autism, with abnormalities reported in neurons in the basal forebrain (Bauman Kemper, 1994). Perry et al. (2001) found extensive loss of high affinity nicotinic receptors from the neocortex (frontal and parietal), and from the cerebellum (Lee, et al., in preparation). Nicotinic receptors are implicated in attention, and also consciousness as many general anaesthetics block the receptor channel (Chapter 9). 

Unlike most general anaesthetics, xenon does not enhance the activity of the inhibitory GABAA receptors. Instead, it appears to have a... 

RECEPTOR ANTAGONIST (channel-blocking at NMDA receptors). It is an OPIOID ANALGESIC, (dissociate) GENERAL ANAESTHETIC, PSYCHOTROPIC and ANTICONVULSANT. It iS a drug of abuse and has been withdrawn from human clinical use. etidocaine [ban, inn, usan] (Duranest ) is an amide series LOCAL ANAESTHETIC, used by injection for infiltration and regional pain relief. 

The protein theory is currently considered more likely to explain the process of anaesthesia, because general anaesthetics affect synaptic transmission rather than axonal conduction. Both the release of transmitter and the response of the postsynaptic receptors are affected. 

Nucleic acids like DNA are important drug receptors, e.g. for chemicals controlling malignancy such as inter-colator agents. Finally, general anaesthetics interact with and alter the structure and function of the lipids of the cellular membrane. 

General anaesthetics have been in use for more than a centuiy, but unfortunately so far no exact mechanism of action has been put forward. Of coiuse, a few theories, namely lipid, physical, biochemical, miscellaneous, Meyer-Overton, minimum alveolar concentration (MAC), stereochemical effects and ion-channel and protein receptor theories have been advocated from time to time in support of the mode of action of the general anaesthetics. These will be discussed briefly in this context. 

Mechanism The most pivotal theme to explain the actual mechanism of action of volatile (general) anaesthetics logically and legitimately involves the interaction of the anaestheties with the receptors which critically regulate the performance of the ion-channels, such as K, Cl or with the ion-channel in a direct fashion (e.g., Na ). 

Franks, N.P. and Lieb, W.R. 1984. Do general anaesthetics act by competitive binding to specific receptors Nature 310 599-601. 

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