title: Quantification of acetylcholine, choline, betaine, and dimethylglycine in human plasma and urine using stable-isotope dilution ultra performance liquid chromatography-tandem mass spectrometry.
abstract: Disorders in choline metabolism are related to disease conditions. We developed a stable-isotope dilution ultra performance liquid chromatography-mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification of acetylcholine (ACh), betaine, choline, and dimethylglycine (DMG). We used this method to measure concentrations of the analytes in plasma and urine in addition to other biological fluids after a protein precipitation by acetonitrile. The detection limits were between 0.35 nmol/L (for ACh in urine) and 0.34 μmol/L (for betaine in urine). ACh concentrations were not detectable in plasma. Intraassay and interassay coefficient of variation (CVs) were all <10.0% in biological fluids, except for DMG in cerebrospinal fluid (CV=12.44%). Mean recoveries in urine pool samples were between 99.2% and 103.9%. The urinary excretion of betaine, choline, and DMG was low, with approximately 50.0% higher excretion of choline in females compared to males. Median urinary excretion of ACh were 3.44 and 3.92 μmol/mol creatinine in males and females, respectively (p=0.689). Plasma betaine concentrations correlated significantly with urinary excretions of betaine (r=0.495, p=0.027) and choline (r=0.502, p=0.024) in females. Plasma choline concentrations correlated significantly with urinary excretion of ACh in males (r=0.419, p=0.041) and females (r=0.621, p=0.003). The new method for the simultaneous determination of ACh, betaine, choline, and DMG is sensitive, precise, and fast enough to be used in clinical investigations related to the methylation pathway.
authors.affiliation: Saarland University Hospital, Department of Clinical Chemistry and Laboratory Medicine, Building 57, 66421 Homburg/Saar, Germany.
authors.forename: Susanne H
authors.initials: SH
authors.lastname: Kirsch
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herrmann
authors.forename: Yannick
authors.initials: Y
authors.lastname: Rabagny
authors.forename: Rima
authors.initials: R
authors.lastname: Obeid
mesh_terms: D000109:Acetylcholine / Q000032:analysis* / Q000097:blood / Q000652:urine; D000328:Adult; D001622:Betaine / Q000032:analysis* / Q000097:blood / Q000652:urine; D002794:Choline / Q000032:analysis* / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D005260:Female; D006801:Humans; D007553:Isotope Labeling; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012521:Sarcosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood / Q000652:urine; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D001622:Betaine; C025138:dimethylglycine; D002794:Choline; D000109:Acetylcholine; D012521:Sarcosine