Norepinephrine Metabolism in Humans Studied by Deuterium Labelling: Turnover of 4–Hydroxy-3–methoxyphenylglycol |
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Authors: | Göran Mårdh Birgitta Sjöquist Erik Änggård |
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Institution: | Department of Alcohol and Drug Addiction Research, Karolinska Institute, Stockholm, Sweden |
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Abstract: | Abstract: D, L(±)-4-Hydroxy-3-methoxyphenylglycol (HMPG) labelled with three deuterium atoms was used to study turnover of plasma free HMPG following an intravenous injection. Ten healthy men were given a pulse dose of either 4.3 μmol or 2.2 μmol of labelled HMPG (2H3]HMPG piperazine salt). Plasma and urine levels of both endogenous and labelled HMPG were subsequently followed by gas chromatography-mass spectrometry with selected ion detection. Kinetic calculations based upon a single-compartment model were consistent with a monoexponential elimination of plasma free HMPG. The half-life of HMPG was 0.46 and 0.78 h (mean values in the two dose groups). The HMPG production rate was 2.01 and 2.35 μmol/hour, and the urinary excretion rate of HMPG (free and conjugated) was 0.48 and 0.47 μmol/h. The endogenous plasma level of free HMPG was 25 and 33 nmol/L. The results show that HMPG turns over rapidly and that HMPG is further metabolized extensively. About one-fourth of the HMPG produced is excreted in urine as free and conjugated HMPG. |
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Keywords: | Norepinephrine 4 - Hydroxy - 3 - methoxyphenylglycol 4 - Hy -droxy-3–methoxymandelic acid Kinetics Gas chromatography-mass spectrometry |
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