• Carlos Venâncio, Luís Félix, Vanessa Almeida, João Coutinho, Luís Antunes, Francisco Peixoto, and Teresa Summavielle.
• From the *Centre for the Research and Technology of Agro-Environmental and Biological Sciences, CITAB, University of Trás-os-Montes and Alto Douro, UTAD, Quinta de Prados, Vila Real, Portugal; †Laboratory Animal Science, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal; ‡Chemistry Centre, Universidade de Trás-os-Montes e Alto Douro, UTAD, Vila Real, Quinta de Prados, Vila Real, Portugal; and §Addiction Biology Group, IBMC - Instituto de Biologia Molecular e Celular, Porto, Portugal.
• Anesth. Analg.. 2015 Feb 1;120(2):320-8.

BackgroundKetamine is often associated with altered mitochondrial function and oxidative stress. Nevertheless, limited data are still available regarding the in vivo action of ketamine in mitochondrial bioenergetics and redox state. Accumulating evidence supports a role for nitric oxide (NO) as a possible modulator of ketamine's side effects. In the present study, we investigated the role of NO modulation on ketamine anesthesia at the level of brain mitochondrial function and redox status.MethodsAdult male rats received a single dose of ketamine (50, 100, or 150 mg/kg IP) or a combination of ketamine and N-nitro-L-arginine (3 mg/kg IP). Animals were killed 6 hours after treatment. Brain and blood samples were collected for plasma NO determination and mitochondria isolation. Several variables of brain mitochondrial function were evaluated.ResultsKetamine interfered with complex I function, revealing increased oxygen consumption in state 4, impaired oxidative phosphorylation efficiency of glutamate-malate substrate, and decreased NADH-ubiquinone oxidoreductase activity. In addition, mitochondrial NO synthase (mtNOS) activity and NO plasma levels were increased for the 50 and 100 mg/kg doses. Ketamine administration increased hydrogen peroxide generation and triggered superoxide dismutase activity. All these effects could totally or partially be prevented by mtNOS inhibition through N-nitro-L-arginine.ConclusionsAcute ketamine administration impaired the function of mitochondrial complex I leading to increased mtNOS activity, increased generation of hydrogen peroxide and NO, resulting in superoxide dismutase triggering, and improved antioxidant activity. The present findings clarify the role of NO modulation in ketamine anesthesia, providing new data on a relevant clinical mechanism.

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