Effects of ketamine on noradrenaline release from the locus coeruleus in rabbits / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of ketamine on the release of norepinephrine(NE)fromlocus coeruleus in the brain of rabbits,trying to elucidate the central mechanism of cardio-vascular responseinduced by ketamine.Methods Nine healthy male New Zealand rabbits weighing 2.0-2.5 kg were used in thisstudy.A trocar(0.8 mm in diameter)was inserted into locus coeruleus using the stereotactic technique and fixed.Four days later push-pull perfusion of the brain was performed.37℃ artificial cerebrospinal fluid(aCSF)wasinfused through the trocar at 0.1 ml?min~(-1).A loading dose of ketamine 2 mg?kg~(-1) was given i.v.followed byketamine infusion at 50 ?g?kg~(-1)?min~(-1) for 20 min.The perfusate from locus coeruleus was collected before duringand after ketamine infusion every 20 min.The NE concentration of the perfusate was measured by high performanceliquid chromatography(HPLC).Results The NE concentration of perfusate from locus coeruleus increasedsignificantly after ketamine infusion from(16?3) pg～?l~(-1) to(32?4)pg??l~(-1) and returned to baseline level 20min after termination of ketamine infusion.Conclusion Ketamine increases the concentration of NE in locuscoeruleus.The increased NE release from locus coeruleus may explain the central mechanism of circulatoryexcitement induced by ketamine.