A method for determination of 3,4-dihydroxyphenylacetic acid and 3,4-dihydroxymandelic acid in urine

Biogenic amines and their metabolites in body fluids of normal, psychiatric and neurological subjects

The biogenic monoamines and their metabolites have been isolated, identified and quantified in human body fluids over the past forty years using a wide variety of chromatographic separation and detection techniques. This review summarizes the results of those studies on normal, psychiatric and neurological subjects. Tables of normal values and the methods used to obtain them should prove to be useful as a reference source for benchmark amine and metabolite concentrations and for successful analytical procedures for their chromatographic separation, detection and quantification. Summaries of the often contradictory results of the application of these methods to psychiatric and neurological problems are presented and may assist in the assessment of the validity of the results of experiments in this field. Finally, the individual, environmental and the methodological factors affecting the concentrations of the amines and their metabolites are discussed.

Effect of methylmercury exposure on different neurotransmitter systems in rat brain

The effect of methylmercury (4.0 mg/kg/day, for 50 days) exposure was studied on various neurotransmitter systems in hypothalamus, pons-medulla, brain-stem, and striatum of rats. Although methylmercury exposure resulted in marked increases in dopamine (DA) content of various brain regions and in the brain-stem or striatal norepinephrine (NE) level, the level of metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) was markedly decreased in the same regions. On the other hand, concentrations of 5-hydroxyindoleacetic acid (5-HIAA) in various brain regions were considerably decreased in methylmercury-exposed rats. Similarly, the 5-hydroxytryptamine (5-HT) level was markedly decreased in the hypothalamus, brain-stem, and striatum.

Demethylation in erythrocytes: a reaction involving hemoglobin

A reaction is described in erythrocytes of rat and of man whereby O-methylated metabolites of the catecholamines are demethylated to the corresponding catechols. The reaction was studied by incubating aliquots of erythrocyte lysates with radiolabeled O-methylated compounds and isolating the catechol product by alumina adsorption chromatography. The demethylating activity was located in the cytosol of the erythrocytes. Evidence was strong that oxyhemoglobin was responsible for the reaction: the demethylase activity was inseparable from oxyhemoglobin in several chromatographic separations. In addition, although commercially available hemoglobins were inactive in the reactions, after their conversion to oxyhemoglobin and purification, they did effect demethylation. Methemoglobin did not demethylate guaiacols and in fact inhibited demethylation by oxyhemoglobin. The reaction was inhibited by the addition of reduced pyridine nucleotides and of the methyl acceptor tetrahydrofolic acid.

Rapid procedure for chromatographic isolation of DOPA, DOPAC, epinephrine, norepinephrine and dopamine from a single urinary sample at endogenous levels

A three-step procedure has been investigated to extract 3,4-dihydroxyphenylalanine (DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), epinephrine (E), norepinephrine (NE) and dopamine (DA) from a single urinary sample with the object of obtaining extracts pure enough for specific fluorimetric assay. The procedure described in this paper results from the combination of urine purification on an aluminum oxide column, separation by ion-exchange chromatography of the DOPA-DOPAC fraction from catecholamines, and ether isolation of DOPAC from DOPA. The whole procedure is rapid and easily performed in one work day. Extraction recoveries were 72.4 +- 3.5%, 76 +- 2%, 85.7 +- 3.3%, 85.6 +- 1.4% and 92.4 +- 5.5% for DOPA, DOPAC, E, NE and DA respectively (n=6). The lowest amounts of the five catechols that could be detected in urinary samples by a combination of this extraction procedure and the methods of assay used in our laboratory were 15 ng for DOPA, 40 ng for NE, 20 ng for E, 152 ng for DA and 2.95 micrograms for DOPAC. Urinary volumes convenient for accurate estimation of each compound were 20 ml for healthy human subjects. For pathological or pharmacological purposes, 5 ml of human urine were sufficient. The daily excretion of DOPA, DOPAC, E, NE and DA found by this procedure agrees with data obtained by other authors in healthy subjects. In pathological samples, our three-step procedure led to lower amounts than methods using alumina purification only. The discrepancies between the two methods are discussed in terms of development of internal standards, relative specificity of fluorimetric assays, values of blank eluates, and the possibility of interference from unknown abnormal body metabolites or pharmacological drugs not eliminated by a single-step alumina purification.