Vanilmandelic acid (VMA), free and conjugated 3-methoxy-4-hydroxyphenylglycol (MHPG) in human ventricular fluid

Selected ion monitoring analysis of monoamine metabolites in cerebrospinal fluid. Application to the study of in vivo effects of alpha 2-antagonists

The technique of isotope dilution mass spectrometry has been used for the measurement of biogenic amine metabolites in cerebrospinal fluid (CSF). CSF samples were collected from rabbits treated with alpha 2-antagonists. The aim of our study was to determine the specificity of these drugs on the central nervous noradrenergic, dopaminergic and serotonergic activity as measured by the release of corresponding monoamine metabolites. 3-Methoxy-4-hydroxyphenylethylene glycol (MHPG) and vanilmandelic acid (VMA) were used as parameters for the noradrenergic activity, whereas homovanillic acid (HVA) and 5-hydroxyindole-3-acetic acid (5-HIAA) were employed to follow the dopaminergic and serotonergic activity, respectively. For the measurement of the biogenic amine metabolites a published GCMS method has been adapted. Samples of 200 microliters CSF were processed. Following addition of deuterated internal standards and acidification, extraction was carried out with ethyl acetate. Preliminary experiments with the analysis of MHPG using diethyl ether for extraction gave rise to emulsion formation and resulted in poor recoveries for MHPG and in irreproducibility problems due to a preferential extraction of non-labelled MHPG, effects which were not observed with ethyl acetate extraction. Derivatization was done with a mixture of pentafluoropropionic anhydride/pentafluoropropanol (or hexafluoroisopropanol) in order to derivatize both hydroxyl and carboxylic acid groups. The derivatization procedure was optimized for the analysis of 5-HIAA by carrying out a second reaction step with pentafluoropropionic anhydride alone in order to complete the derivatization for the indolic NH moiety. The molecular ions of the derivatized products were selected for detection.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies on 3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxyphenylglycol (DHPG) levels in human urine, plasma and cerebrospinal fluids, and their significance in studies of depression

Both concentrations of total 3-methoxy-4-hydroxyphenylglycol (MHPG) and 3,4-dihydroxyphenylglycol (DHPG) in the human urine, plasma and CSF were determined with a high-pressure liquid chromatography with electrochemical detection in order to clarify the dynamic change in these noradrenaline metabolites. Three different biological fluids were collected simultaneously from 16 orthopedic patients who were regarded clinically as substitutes for normal subjects. In the urine, the MHPG concentrations were 1.67 +/- 0.65 micrograms/mg creatinine (mean +/- S.D.) and DHPG 0.39 microgram/mg creatinine +/- 0.21. The plasma levels were 21.16 ng/ml +/- 9.58 for MHPG, and 19.58 ng/ml +/- 8.13 for DHPG. The CSF levels of MHPG and DHPG were 24.08 ng/ml +/- 8.10 and 34.76 ng/ml +/- 11.46, respectively. The CSF levels of these metabolites were correlated significantly with those in the plasma (r = 0.852, p less than 0.001 for MHPG; r = 0.799, p less than 0.001 for DHPG), while no significant correlations were found between the urinary levels and either the plasma or CSF levels of these metabolites. In the urine, the MHPG levels were proportional to the DHPG levels, while the former were inversely proportional to the latter in the plasma or CSF. Neither the MHPG nor DHPG levels in the urine from depressed patients revealed to have any significant correlation with their clinical assessments using the Hamilton Rating Scale Score (HRS). The patients were treated with an antidepressant active selectively on the noradrenergic system, and no significant changes in urinary excretion of these metabolites were observed before and after the drug treatment. These findings suggest that in the case of psychiatric disorders such as depression, these compound levels in the plasma or CSF would provide more important information than those in the urine.

A gas chromatographic-mass spectrometric (GC-MS) assay for 3-methoxy-4-hydroxyphenethyleneglycol and vanilmandelic acid in human serum

Procedure for the quantification of 3-methoxy-4-hydroxyphenethyleneglycol (MHPG) and vanilmandelic acid (VMA) in human serum are described. MHPG was selectively acetylated then determined as its 4-acetyl-di-trifluoroacetyl derivative and VMA as its di-pentabluoropropionyl-methyl ester. Deuterium-labeled MHPG and VMA were used as internal standards. Each of these metabolities and the resprective internal standards was recorded by double ion monitoring respectively, and the ratios were determined for specificity. Assay sensitivities of 1.0 ng/ml for MHPG and 2.0 ng/ml for VMA were achieved using 0.5 ml of serum. Total and free MHPG concentrations in human serum were determined to be 16.5 ng/ml +/- 4.4 (S.D.) and 4.6 ng/ml +/- 1.0 respectively from 10 normal male subjects. Free VMA concentrations were 7.0 ng/ml +/- 1.5; thus the ratio of MHPG/VMA was calculated to be 2.4 +/- 0.7 in these subjects. Of these two major normal metabolites of norepinephrine, MHPG is regarded to be largely derived from the central nervous system while VMA is from the periphery. The procedures are highly specific as well as simple and sensitive enough to permit simultaneous measurement of these two metabolites in a series of multiple samples from an individual.

Profiling of human body fluids in healthy and diseased states using gas chromatography and mass spectrometry, with special reference to organic acids

This review summarizes recent advances in the application of gas chromatography and mass spectrometry to the study of human diseases. Emphasis is placed upon the organic acid profiles of the various body fluids. Methods for sample work-up prior to separation and mass spectrometric analysis are reviewed, and artifacts and pitfalls are discussed. Organic acid profiles, obtained with packed or capillary columns attached to mass spectrometers with or without computer systems, have led to the discovery of new normal metabolites, new metabolic disorders, and to new knowledge about a number of other diseases. Stable isotopes and gas chromatography--mass spectrometry are suitable for quantitative analysis of many compounds in the body fluids, and well suited for investigation of metabolic pathways.

Presence of free, sulfate and glucuronide conjugated 3-methoxy-4-hydroxyphenylglycol (MHPG) in human brain, cerebrospinal fluid and plasma

The concentration of the free, glucuronide and the sulfate conjugated forms of 3-methoxy-4-hydroxyphenylglycol (MHPG) were measured in human plasma, cerebrospinal fluid (CSF) and brain by mass fragmentography. All three forms of MHPG were detected in the media analyzed. Free MHPG was found to be the predominant form in both the brain and the CSF. The sulfate conjugate of MHPG constitutes about 15% of the total MHPG in the CSF while in the brain the percentage varies between 30% in the hypothalamus and cortex and 80% in the substantia nigra. The concentration of the glucuronide conjugate of MHPG measured in the brain and CSF represents about 5% of the total MHPG concentration. In the plasma free MHPG and its glucuronide and sulfate conjugates are present in about equal concentrations. The relative concentrations of the three forms of MHPG measured in plasma, CSF and brain were compared with their concentrations in the urine from previously published results. From this comparison the diagnostic significance of each of the three forms of MHPG in the clinical assessment of central norepinephrine metabolism is discussed.