24 h Excretion Patterns of Free, Conjugated and Methylated Catecholamines in Man

Abstract

Siunmary:A method based on high performance liquid chromatography with electrochemical detection is described for quantification of adrenaline, noradrenaline, dopamine (free and total), metanephrine, normetanephrine, and 3-methoxytyramine (free) in urine samples. Purification of the samples is achieved on disposable -Rad ion-exchange columns in combination with small Sephadex G 10 columns. A clear circadian rhythm was found in the 24 h excretion pattern of free adrenaline and noradrenaline for 4 volunteers (city bus drivers during a working day). No rhythms were seen in the 24h excretion pattern of free or conjugated dopamine, conjugated adrenaline or conjugated noradrenaline, or of the methylated free catecholamines. It is concluded that in order to obtain Information about the neurotransmitter function of peripheral catecholamines it is sufficient to determine the non-conjugated compounds; values for the conjugated and methylated metabolites contribute no extra Information. 24-Stunden^-Ausscheidungsmuster der freien, konjugierten und methylierten Katecholamine beim MenschenZusammenfassung: Eine Methode zur quantitativen Bestimmung von Adrenalin, Noradrenalin, Dopamin (freies und gesamtes), Metajjephrin, Normetanephrin und 3-Methoxytyramin (freies) im Harn auf der Grundlage der Hochleistungsflüssigchromatographie mit elektrochemischer Detektion wird beschrieben. Die Reinigung der Proben wird durch Einmäl-Ionenaustauscher-Säulen ( -Rad) in Kombination mit kleinen Sephadex G -Säulen erreicht. Bei vier Busfahrern wurde während eines Arbeitstages ein deutlicher circadianer Rhythmus im 24^Stunden*Ausscheidungsmuster für freies Adrenalin und Noradrenalin gefunden. Für freies öder konjugiertes Dopamin, konjugiertes Adrenalin, konjugiertes Noradrenalin oder die methylierten freien Katecholamine wurde keine Rhythmik im 24-Stunden-Ausscheidungsmuster beobachtet. Wir schließen daraus, daß es für den Erhalt von Informationen über die Neurotransmitterfunktion der peripheren Katecholamine ausreicht, die nicht-konjügierten Verbindungen zu bestimmen; Werte für die konjugierten und methylierten Metabolite erbringen keine weitere Information.is some recent evidence that also methylated catecholIntroduetion amines should be taken into account äs indices of Psychoendocrine research has emphasized the use of sympathieoadrenal activity (5). It is believed that Ocätecholamines äs indicators of mental stress and methylation of catecholamines by the extraneuronally physical workload (l, 2). Adrenaline (A) excretion localized enzyme, catechol-O-methyl transferase, is appears to be particulary responsive to mental stress, the primary metabolic route for actively released catewhereas urinary noradrenaline responds mainly to cholamine. This enzyme converts noradrenaline, adphysical activity (3, 4). Although studies in this field renaline and dopamine into nonnetanephrine, metaare usually restricted to the free catecholamines, there nephrine, and 3-methoxytyramine, respectively.

Circadian Variations of Urinary Dopamine, Norepinephrine, Epinephrine and Sodium in Normotensive and Hypertensive Subjects

“…The time-related change in urinary DA was statistically significant only in the BHT and in the whole groups although the NT and mild HT showed essentially the same pattern of DA excretion as the BHT. Some investigators have observed significant circadian rhythm in urinary DA [11,22] while others have not [4,19]. Although the reason for these inconsistencies is not clear, differences in study design such as number and age of subjects, environmental conditions, and method for the measurement of DA, may account for them.…”

“…Impairment of central and peripheral dopaminergic function has been suggested in essential hypertension [14,16]. Dopamine may play a role in the physiological regulation of water and Na metabolism since it has been observed that urinary DA increased in response to high Na intake [16,17] and a DA blockade attenuated the natriuresis of saline loading [18], Unlike NE and E, it is controversial whether urinary DA excre tion shows a circadian variation [4,11,19]. There is little published information concerning the relationship be tween circadian excretion of Na and DA, or circadian DA excretion in hypertensive subjects.…”

Synthetic calibrators for the analysis of total metanephrines in urine: Revisiting the conditions of hydrolysis

“…Total urinary metanephrines are usually measured after an acid hydrolysis step or more rarely by enzyme treatment with arylsulfatase to cleave the sulfate moiety from the phenolic group [7][8][9][10][11][12][13][14][15][16][17].…”

“…Metanephrines in free form are measured by HPLC with electrochemical or fluorimetric detection, using calibrators prepared inhouse by weighting free synthetic metanephrines or using certified calibrators provided by commercial distributors such as BioRad, Chromsystems or RECIPE [7][8][9][10][11][12][13][14][15][16][17]. It has been reported that most metanephrines present in calibrators and quality controls are free rather than sulfoconjugated forms [18].…”

“…Further adaptations led to routine procedures in clinical laboratories where acidic treatment at pH values ranging from 0.5 to 1.1 and incubation time from 20 to 45 min are commonly applied [7][8][9][10][11][12][13][14][15][16][17]. The problem is that, should shortcomings occur at this step (e.g., insufficient acidification), or should this step be omitted, the commercially available quality control samples will fail to alert the analyst.…”