Mass fragmentographic determination of 4-hydroxy-3-methoxymandelic acid in human urine, cerebrospinal fluid, brain and serum using a deuterium-labelled internal standard

Urinary catecholamine metabolites in borderline and established hypertension. Relationship to body composition

The urinary excretion of catecholamine metabolites was studied by means of gas chromatography-mass spectrometry in 38 hypertensive patients on a moderately sodium-restricted diet during hospitalization. Twenty-four patients had established hypertension (EHT) and 14 borderline hypertension (BHT) with mean basal morning blood pressures of 155 +/- 14/101 +/- 8 and 132 +/- 9/87 +/- 4 mmHg, respectively. In these two groups of hypertensive patients the mean daily excretion of 4-hydroxy-3-methoxymandelic acid (VMA) was 13.3 +/- 5.9 vs. 14.0 +/- 6.3 nmol/ml and of 4-hydroxy-3-methoxy-phenylglycol (HMPG) 7.8 +/- 4.1 vs. 7.0 +/- 3.9 nmol/ml. These concentrations were not significantly different from the corresponding values of 18 normotensive control persons (mean ambulatory blood pressure 121 +/- 10/74 +/- 9 mmHg, VMA 12.3 +/- 5.5 nmol/ml, HMPG 9.6 +/- 3.9 nmol/ml). The normotensive individuals excreted 23.7 +/- 8.9 nmol/ml of homovanillic acid (HVA), while the two groups of hypertensive patients showed significantly lower HVA excretion, EHT 17.6 +/- 6.2 nmol/ml and BHT 16.1 +/- 5.9 nmol/ml (p less than 0.05). Our findings support the view that no generalized increase in sympathetic activity exists in EHT or BHT. In BHT, but not in EHT, there were correlations between catecholamine metabolite excretion and body weight. The biological significance of the lower HVA concentrations in hypertensive patients compared to control individuals is not clear.

Prolonged symptoms of brain dysfunction--adverse effect of levodopa

Symptoms of brain dysfunction occurred in a 67-year-old woman with idiopathic parkinsonism on treatment with levodopa. The adverse effect reappeared in a more severe and prolonged form when she was treated one year later with levodopa in combination with the peripheral decarboxylase inhibitor Ro-4-4602. The symptoms were associated with a markedly altered level of HMPG (a noradrenaline metabolite) in the cerebrospinal fluid.

Measurement of plasma vanillylmandelic acid by liquid chromatography with electrochemical detection

A liquid chromatographic method with electrochemical detection is described for measuring plasma 3-methoxy-4-hydroxymandelic acid (VMA). Plasma is deproteinized by gel filtration and VMA is extracted into ethyl acetate, which is evaporated. VMA is oxidized to vanillin, which is purified by toluene extraction and quantified by high-performance liquid chromatography. The recovery of VMA through the entire procedure is 52 +/- 10% (mean +/- S.D., n = 19). The plasma VMA concentration in healthy young volunteers varies between 4.39 and 14.6 ng/ml, a range that is in excellent agreement with data obtained with mass fragmentography.

Human class I alcohol dehydrogenases catalyze the oxidation of glycols in the metabolism of norepinephrine

Investigations of the function of human liver alcohol dehydrogenase (ADH) in norepinephrine metabolism have revealed that class I ADH catalyzes the oxidation of the intermediary alcohols 4-hydroxy-3-methoxyphenyl glycol (HMPG) and 3,4-dihydroxyphenyl glycol (DHPG) in vitro. The kcat/Km values for the individual homogeneous class I isozymes are generally in the range from 2.0 to 10 mM-1 X min-1, slightly lower than those obtained for ethanol oxidation, 16-66 mM-1 X min-1, but considerably higher than those obtained for ethylene glycol oxidation, 0.23-1.5 mM-1 X min-1. Importantly, HMPG and DHPG are not substrates for the class II or class III ADHs. 4-Methylpyrazole and 1,10-phenanthroline inhibit the class I ADH-catalyzed oxidation of HMPG, DHPG, and ethanol with inhibition constants of 75-90 nM and 19-22 microM, respectively, indicating that these substrates interact at the same catalytic site of ADH. Moreover, ethanol inhibits the oxidation of HMPG. The competition of ethanol with HMPG for ADH provides a basis for the in vivo changes observed in norepinephrine metabolism after acute ethanol intake. Any assessment of norepinephrine function through the study of metabolites in peripheral body fluid must include monitoring the oxidation of HMPG by ADH.

Vanillic acid, a metabolite of 4-hydroxy-3-methoxyphenylglycol and 4-hydroxy-3-methoxymandelic acid in man

4-Hydroxy-3-methoxyphenylglycol (HMPG) labelled with 14C was used to study the metabolic fate of HMPG in six healthy volunteers. Besides conjugation and oxidation to 4-hydroxy-3-methoxymandelic acid (HMMA, VMA) a minor portion, 8.4 +/- 1.1% (mean +/- SEM) was excreted as 14C-labelled vanillic acid (VA). To study if VA was formed from HMPG or HMMA (VMA), deuterium-labelled HMPG [( 2H3]HMPG) and HMMA [( 2H6]HMMA) were simultaneously injected intravenously to seven healthy volunteers. The recovery of [2H3]VA from [2H3]HMPG was 8.3 +/- 2.1% and the recovery of [2H6]VA from [2H6]HMMA was 9.0 +/- 2.1%. The 2H-labelled VAs were probably formed by a decarboxylation reaction, in the case of HMPG after previous oxidation to HMMA.

Central and peripheral metabolites of norepinephrine and dopamine in postmenopausal women

Urinary 3-methoxy-4-hydroxyphenylglycol (MHPG) sulfate and glucuronide reflect, in part, central norepinephrine activity while urinary 3-methoxy-4-hydroxymandelic (VMA) reflects peripheral norepinephrine activity. Urinary MHPG and VMA were measured, together with homovanillic acid (HVA), in 20 symptomatic and seven asymptomatic postmenopausal women and 10 premenopausal control women. Urinary HVA reflects, in part, central dopamine metabolism. After nine of the symptomatic women were treated for 2 months with 0.625 mg of conjugated estrogens, urinary catecholamine measurements were repeated. Serum estrogen levels were not different in symptomatic and asymptomatic patients. Urinary MHPG, VMA, and HVA were similar in symptomatic women before and after estrogen treatment and were not different from levels of asymptomatic postmenopausal and control subjects. The ratios of MHPG:VMA, MHPG:HVA, and VMA:HVA also were similar. While body weight and estrogen did not correlate with urinary catecholamines, there was a significant positive correlation between MHPG and age in postmenopausal subjects (r = 0.56, p less than 0.005).

Mass fragmentographic determination of homovanillic and 4-hydroxy-3-methoxy mandelic acids in 50 microliter plasma

A method is presented for the mass fragmentographic determination of homovanillic and 4-hydroxy-3-methoxy mandelic acids in 50 microliter plasma or serum. The values found in normal, healthy adults agree well with previously published reports which required, however, much larger plasma volumes. The method uses a simple ethyl acetate extraction from acidified plasma and a one-step derivatisation with trifluoroethanol and pentafluoropropionic anhydride. The deuterium-labelled analogues are used as internal standards.

Assay of urinary vanilmandelic, homovanillic, and 5-hydroxyindole acetic acids by liquid chromatography with electrochemical detection

A reversed-phase liquid chromatographic method with amperometric detection has been developed for the simultaneous determination of the noradrenaline metabolite, vanilmandelic acid, the dopamine metabolite, homovanillic acid, and the serotonin metabolite, 5-hydroxyindole acetic acid, in human urine. After purification by an extraction procedure, the metabolites were rapidly separated under isocratic conditions. Detection and quantification were performed with an electrochemical detector using a carbon paste electrode. The present method is sensitive, selective and, achieves a high degree of precision by the use of isovanilmandelic acid as an internal standard. This provides a suitable tool for clinical and research applications.

Circadian rhythms of hormones in primary affective disorders

The study of circadian rhythms of hormones in PAD reveals impairments in the hypothalamo-pituitary-adrenal axis, GH, PRL, TSH and melatonin secretion. Twenty-four hour cortisol curves show increased number of secretory episodes, increased duration of each episode, increased amount of total cortisol secretion for each episode and of cortisol secretion per minute. Moreover, secretory bursts appear in the late afternoon-evening, when in normal subjects secretion is blunted. In some cases the acrophase is phase-advanced by 1-4 h. GH nocturnal peak is often blunted. PRL nocturnal secretion may also be low, especially in bipolar patients, or the acrophase is 6-8 h phase-advanced. Melatonin nocturnal peak may be blunted and abnormal diurnal peaks are sometimes observed. TSH secretion is normal in bipolar patients; in unipolars, the nocturnal peak, the mean 24-h secretion and the ratio sleep/wakefulness are reduced. The acrophase may be advanced.

Psychological stress and increases in urinary norepinephrine metabolites, platelet serotonin, and adrenal androgens in women with polycystic ovary syndrome

Twenty-three women with polycystic ovary syndrome, 10 women with hypothalamic-pituitary dysfunction, and 50 control subjects were studied in an attempt to investigate the prevalence of psychological stress and its possible relationship to various hormonal parameters. Norepinephrine (NE) excretion, as reflected by urinary 3-methoxy-4-hydroxyphenylglycol (MHPG), and urinary 3-methoxy-4-hydroxymandelic acid (VMA), platelet serotonin, plasma adrenocorticotrophic hormone (ACTH), urinary free cortisol, serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), androstenedione (Adione), dehydroepiandrosterone (DHEA), its sulfate (DHEA-S), delta 5-androstenediol (delta 5-Adiol), testosterone (T), and unbound estradiol (E2) were measured. In addition, psychological stress was assessed by means of questionnaires modified from the Schedule of Recent Experiences, in which a Life Events Inventory was scored between 1 and 100. Women with polycystic ovary syndrome had significantly elevated levels of serum LH, LH:FSH ratios, unbound E2, Adione, DHEA, delta 5-Adiol, T, and DHEA-S (p less than 0.01). The number of Major Life Events (events scored on the questionnaire above 60) was significantly higher in women with polycystic ovary syndrome than in control women and women with hypothalamic-pituitary dysfunction (p less than 0.05). Urinary MHPG and platelet serotonin levels were also significantly higher in women with polycystic ovary syndrome (p less than 0.05), whereas VMA was normal. Levels of plasma ACTH and urinary free cortisol were similar in all groups. There was a significant positive correlation between MHPG and DHEA-S, MHPG and LH, and LH and T levels in women with polycystic ovary syndrome and those with hypothalamic-pituitary dysfunction (p less than 0.01). VMA also correlated with DHEA-S (p less than 0.05). In conclusion, psychological stress may be more prevalent in women with polycystic ovary syndrome and may be associated with elevated levels of MHPG and platelet serotonin. Because we have found that MHPG, but not VMA, correlated with LH, and because both MHPG and VMA correlated with DHEA-S, we hypothesize here that psychological stress and neurotransmitter levels may be linked to some of the hormonal derangements, including inappropriate gonadotropin secretion and elevated adrenal androgen levels in women with polycystic ovary syndrome.

Norepinephrine metabolism in man using deuterium labeling: turnover 4-hydroxy-3-methoxymandelic acid

4-Hydroxy-3-methoxymandelic acid (HMMA; VMA) labeled with three deuterium atoms was used to study the turnover and fate of HMMA following intravenous injection. Five healthy men were given a pulse dose of 5.0 mumol of labeled HMMA. Plasma and urinary levels of both endogenous and labeled HMMA were subsequently followed by gas chromatography-mass spectrometry using selected ion detection. The kinetic parameters were determined both with and without compensation for the pool expansion caused by the injection of labeled HMMA. The urinary recovery of labeled HMMA was 85 +/- 10% (mean +/- SD). No conversion of HMMA to 4-hydroxy-3-methoxyphenyl glycol (HMPG) occurred. The biological half-life of HMMA was 0.54 +/- 0.22 h. The apparent volume of distribution was 0.36 +/- 0.11 L/kg. The production rate or body turnover was 1.27 +/- 0.51 mumol HMMA/h and urinary excretion rate was 0.82 +/- 0.22 mumol/h. These results show that HMMA is turnover over rapidly in a relatively small volume of distribution and that, unlike HMPG, it is an end metabolite of norepinephrine in man.

Plasma and cerebrospinal fluid 3-methoxy-4-hydroxyphenylethylene glycol (MHPG) as indices of brain norepinephrine metabolism in primates

The relationship between MHPG concentration in several brain areas, cisternal CSF and plasma was examined in 26 vervet monkeys. Free MHPG was measured by gas chromatography-mass spectrometry using deuterated MHPG as internal standard. In animals with or without treatment with drugs that alter norepinephrine metabolism, highly significant correlations were found in concentrations of MHPG between the various brain areas, between plasma and CSF, between plasma and brain areas and between CSF and brain areas. The concentration of MHPG in CSF was higher than in plasma and with the exception of occipital cortex, all brain regions contained a higher concentration of MHPG than CSF. This study supports the notion that free MHPG concentrations in plasma and cisternal CSF are useful indices of central noradrenergic activity.

Norepinephrine metabolism in man using deuterium labelling: the conversion of 4-hydroxy-3-methoxyphenylglycol to 4-hydroxy-3-methoxymandelic acid

4-Hydroxy-3-methoxyphenylglycol (HMPG) labelled with three deuterium atoms was used to study the disposition of peripherally administered HMPG. Five healthy men were given an intravenous pulse dose of 4.3 mumol of labelled HMPG and subsequent plasma and urine levels of endogenous and labelled HMPG as well as those of 4-hydroxy-3-methoxymandelic acid (HMMA, VMA) were determined by gas chromatography-mass spectrometry, using selected ion detection. Approximately 40% of the injected amount of deuterium-labelled HMPG was recovered in the urine as HMMA and another 40% was eliminated as HMPG conjugates. Thus, the HMPG formed from norepinephrine either in the central or peripheral nervous system undergoes both conjugation and extensive oxidation.

Deficient sympatho-adrenal activity-a cause of apnoea? Urinary excretion of catecholamines and their metabolites in preterm infants

Catecholamines (CA) and the CA metabolites 4-hydroxy-3-methoxyphenyl-glycol (HMPG) and 4-hydroxy-3-methoxymandelic acid (VMA) have been determined in 8 preterm infants with recurrent apnoea and in 6 infants with the same birth weight total CA, HMPG or VMA excretion was found during the second, fifth and twelfth day, except for adrenaline, which was higher in the low-apnoeic group during one day.

Catecholamine metabolites in amniotic fluid as indicators of intrauterine stress

The catecholamine metabolites HMPG and VMA have been determined in samples of amniotic fluid in 38 uncomplicated pregnancies, seven cases of IUGR, and six cases of diabetes. A successive increase of HMPG and VMA was found toward the end of the pregnancy. HMPG and particularly the HMPG/VMA ratio were significantly higher in the amniotic fluid of the growth-retarded fetuses than in the uncomplicated cases. No significant difference was found between the diabetic and uncomplicated cases.

Mass fragmentographic determination of vanilmandelic acid, homovanillic acid and isohomovanillic acid in human body fluids

Vanilmandelic, homovanillic and isohomovanillic acids in body fluids were efficiently isolated by liquid chromatography on an Amberlite XAD-4 column and by organic extraction in a special apparatus. The purified metabolites were converted into their trifluoroacetylhexafluroisopropanol esters and analyzed by mass fragmentography. The working curves of the metabolites were linear from 0.5 to 5 ng injected. The minimum detectable concentrations of all the metabolites were 2 ng/ml for plasma and cerebrospinal fluid, and 120 ng/ml for urine. The metabolite concentrations in plasma, cerebrospinal fluid and urine of normal persons and patients were determined.

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.

Modification of the Pisano method for vanilmandelic acid using high pressure liquid chromatography

A method for the measurement of urinary vanilmandelic acid (VMA) is described based on a modification of the colorimetric procedure of Pisano. VMA is oxidized to vanillin with subsequent measurement of the vanillin by high pressure liquid chromatography with electrochemical detection (LCEC). The technique has been successfully applied to a number of human and animal urine samples. Urinary VMA values obtained by the LCEC method are in good agreement with those determined by the method of Pisano. The new method is both more selective and more sensitive than the colorimetric procedure.

Mass fragmentography of 5-hydroxytryptophol and 5-methoxytryptophol in human cerebrospinal fluid

A specific and very sensitive method for the determination of 5-hydroxy-tryptophol (5-HTOL) and 5-methoxytryptophol (5-MTOL) in extracts from human cerebrospinal fluid (CSF) involving the use of mass fragmentography and pentafluoropriopionyl derivatives is described. 5-HTOL and 5-MTOL were determined in human CSF of three patients with leukaemia and from nine patients with neurological disorders. The concentration of free 5-HOT in CSF was in the range of 0.1-33 ng/ml and that of 5-MTOL was 0.3-13.9 ng/ml. For the first time the presence of these compounds in human material has been shown. The concentration of these two alcohols in CSF is markedly lower than the concentration of 5-hydroxyindoleacetic acid. These results suggest that human cerebral 5-hydroxytryptamine is preferentially metabolized to 5-HTOL-hydroxyindoleacetic acid rather than to 5-HTOL and 5-MTOL.

Concentration gradients of monoamine metabolites in human cerebrospinal fluid

The monamine metabolites 5-hydroxyindoleacetic acid (5-HIAA), homovanillic acid (HVA), vanillylmandelic acid (VMA), and 4-hydroxy-3-methoxyphenylglycol (HMPG) were analysed in CSF from different regions of the CSF system to study the caudocranial concentration gradient of the metabolites. Four consecutive 10 ml fractions of CSF were withdrawn in 17 patients during the course of four minutes. The CSF pressure was monitored through a lumbar cannula because of suspected adult hydrocephalus. A pronounced gradient of the HVA concentration was found with a ratio between the last and the first fraction of 1,7. 5-HIAA showed a slight increase while HMPG and VMA showed no increase at higher levels of the CSF system. The results suggest that lumbar HVA reflects dopaminergic activity in the brain, whereas lumbar 5-HIAA and HMPG/VMA reflect the activity of 5-hydroxytryptamine and noradrenaline secreting neurones in both the brain and the spinal cord.