[Role of nitric oxide (NO) in the mechanism of anesthetic action].

Published reports on modifications of nitric oxide (NO) synthase (NOS) activity and NO production in the brain during development of anesthesia induced by the most common inhalational (halothane, isoflurane, sevoflurane, enflurane) and intravenous (ketamine, barbiturates, propofol, etomidate) anesthetics are reviewed. According to a popular universally acknowledged hypothesis, inhibition of NOS activity and blockade of NO neurotransmitter function are important steps in the mechanism of action of anesthetics. There are data which confirm the validity of this hypothesis for all above-listed drugs, but there are also data which disagree with it. Some scientists find that anesthesia has no effect on NOS activity and NO production, others found that the enzyme activity and NOS gene expression increased under the effect of anesthesia. Published reports and authors' data on a drastic increase of NO content in the cerebral cortex in halothane anesthesia are discussed. The effects of narcotics on NO-mediated changes in vascular tone are analyzed.