Biomaterial Database

Cellular and synaptic actions of general anaesthetics. 1992

K Krnjević

Anaesthesia Research Department, McGill University, Montreal, Québec, Canada.

1. This paper briefly reviews mechanisms by which such widely-used volatile anaesthetics as halothane and isoflurane suppress neural function in the brain. 2. In general, anaesthetics tend to depress neuronal firing and excitatory synaptic transmission, and potentiate synaptic inhibition. 3. According to recent evidence, a particular important action of anaesthetics is to inactivate a variety of both voltage-dependent and agonist-triggered Ca-currents. 4. Activation of K outward currents and Na inward currents probably occurs only with higher doses of anaesthetics. 5. How anaesthetics interfere with Ca-channels remains largely a matter of speculation--though some evidence favours a Ca-mediated action, following Ca2+ release from internal stores, that may account also for potentiation of IPSPs by prolonging the opening of GABA-activated Cl- channels. 6. Whatever its precise underlying mechanism, a suppression of Ca-influx into pre-synaptic terminals could well account for the depression of excitatory synaptic transmission.

UI	MeSH Term	Description	Entries
D009474	Neurons	The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.	Nerve Cells,Cell, Nerve,Cells, Nerve,Nerve Cell,Neuron
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000768	Anesthesia, General	Procedure in which patients are induced into an unconscious state through use of various medications so that they do not feel pain during surgery.	Anesthesias, General,General Anesthesia,General Anesthesias
D000777	Anesthetics	Agents capable of inducing a total or partial loss of sensation, especially tactile sensation and pain. They may act to induce general ANESTHESIA, in which an unconscious state is achieved, or may act locally to induce numbness or lack of sensation at a targeted site.	Anesthetic,Anesthetic Agents,Anesthetic Drugs,Anesthetic Effect,Anesthetic Effects,Agents, Anesthetic,Drugs, Anesthetic,Effect, Anesthetic,Effects, Anesthetic
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013569	Synapses	Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.	Synapse