title: An online solid-phase extraction-liquid chromatography-tandem mass spectrometry method to study the presence of thyronamines in plasma and tissue and their putative conversion from 13C6-thyroxine.
abstract: Thyronamines are exciting new players at the crossroads of thyroidology and metabolism. Here, we report the development of a method to measure 3-iodothyronamine (T(1)AM) and thyronamine (T(0)AM) in plasma and tissue samples. The detection limit of the method was 0.25 nmol/l in plasma and 0.30 pmol/g in tissue both for T(1)AM and for T(0)AM. Using this method, we were able to demonstrate T(1)AM and T(0)AM in plasma and liver from rats treated with synthetic thyronamines. Although we demonstrated the in vivo conversion of (13)C(6)-thyroxine ((13)C(6)-T(4)) to (13)C(6)-3,5,3'-triiodothyronine, we did not detect (13)C(6)-T(1)AM in plasma or brain samples of rats treated with (13)C(6)-T(4). Surprisingly, our method did not detect any endogenous T(1)AM or T(0)AM in plasma from vehicle-treated rats, nor in human plasma or thyroid tissue. Although we are cautious to draw general conclusions from these negative findings and in spite of the fact that insufficient sensitivity of the method related to extractability and stability of T(0)AM cannot be completely excluded at this point, our findings raise questions on the biosynthetic pathways and concentrations of endogenous T(1)AM and T(0)AM.
authors.affiliation: Laboratory of Endocrinology, F2-131.1., Department of Clinical Chemistry, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. m.t.ackermans@amc.uva.nl
authors.forename: M T
authors.initials: MT
authors.lastname: Ackermans
authors.forename: L P
authors.initials: LP
authors.lastname: Klieverik
authors.forename: P
authors.initials: P
authors.lastname: Ringeling
authors.forename: E
authors.initials: E
authors.lastname: Endert
authors.forename: A
authors.initials: A
authors.lastname: Kalsbeek
authors.forename: E
authors.initials: E
authors.lastname: Fliers
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002853:Chromatography, Liquid / Q000379:methods*; D057230:Limit of Detection; D008099:Liver / Q000378:metabolism; D051381:Rats; D012680:Sensitivity and Specificity; D052616:Solid Phase Extraction / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013970:Thyronines / Q000032:analysis* / Q000378:metabolism; D013974:Thyroxine / Q000378:metabolism*
chemical_list: C487948:3-iodothyronamine; D013970:Thyronines; C004547:thyronamine; D013974:Thyroxine