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Tyrosine hydroxylase activity correlated significantly with norepinephrine concentration and turnover, when results from regions containing predominantly noradrenergic terminals were compared, and with dopamine concentration and turnover when results from regions containing predominantly dopaminergic terminals were compared. Regions containing dopamine or norepinephrine cell bodies were characterized by higher tyrosine hydroxylase activities as compared to regions containing mostly nerve terminals. Higher levels of tyrosine hydroxylase activity and transmitter turnover were observed in regions containing dopaminergic terminals than in regions containing norepinephrine terminals. These findings are consistent with the view that tyrosine hydroxylase activity is linked to rates of catecholamine utilization by neurons in the CNS.Abbreviations used: TH, tyrosine 3-hydroxylase; aMT, DL-a-methyl-ptyrosine-methylester-HC1; DOPA, 3,4-dihydroxyphen ylalanine.

~ The concentratinn of dopamine (DA) and serotonin (5-HT) metabolites in brain regions \vas not altcred by doses of ketamine (10mgIkg) which induced dissociative anesthesia in a primate species. Crrcopithtwr.5 urrliiops. Fluphena7ine (1.0 mg,'kg) increased homovanillic acid (HVA) content in all brain regions examined. An increase in HVA and 5-hydroxyindoleacetic acid (5-HIAA) concentration was observed in cisternal CSF 4 h after ketamine without a concomitant change in the brain concentration of these metabolites. KFTAMINI (dL2-(0-~hlorophenyl)-2-(-methyIamino)-cyclohexanone) is a dissociative anesthetic used with increasing frequency both as an inducing agent and as ;I general anesthetic. particularly in children (BOVILL ot d . 1971 : S~~S S M A N . 1974). The neurometabolic effects of ketamine in doses comparable to those used in clinical practice (2.(t10.0 mg,kg) are not well known. Studies using much larger doses of ketamine (4& I00 mg.'kg) have provided evidence suggesting that this drug induces an acceleration of dopamine

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