Effect of ketamine on presympathetic neurons in rostral ventrolateral medulla of rats

AIM: To study the effects of ketamine on central sympathetic and cardiovasc ular regulation. METHODS: The experiment was performed on 25 urethane-anaes thetized, artificially ventilated adult rats. A total of 32 presympathetic neurons in the rostral ventrolateral medulla (RVLM) were electrophysiologic ally identified, which had properties of both barosensitivity and projectio n to the spinal cord. Responses of these neurons to intravenously administr ated ketamine (a non-competitive N-methyl-D-aspartate receptor antagonist) were observed. RESULTS: Intravenous injection of ketamine (3, 6, 12 mg/kg b ody weight) increased the firing rate and blocked the barosensitivity of pr esympathetic neurons in the RVLM in a dose-dependant manner. CONCLUSION: Ke tamine could affect the sympathetic outflow by blocking tonic baroreceptor inhibition of the presympathetic neurons in the RVLM.