Leukotriene D₄-d₅(LTD₄-d₅) contains five deuterium atoms at the 19, 19', 20, 20 and 20 positions. It is intended for use as an internal standard for the quantification of LTD₄by GC-or LC-mass spectrometry. LTD₄is one of the constituents of slow-reacting substance of anaphylaxis (SRS-A) produced by the metabolism of LTC₄by γ-glutamyl transpeptidase.^1,2It is the first cysteinyl leukotriene metabolite of LTC₄. Like LTC₄, LTD₄-induced bronchoconstriction and enhanced vascular permeability contribute to the pathogenesis of asthma and acute hypersensitivity.^3,4LTD₄is equipotent to LTC₄in its biological activities, except that LTD₄is nearly 100-fold more effective in the contraction of peripheral airway smooth muscle.^5,6

1.Örning, L., HammarstrÖm, S., and Samuelsson, B.Leukotriene D: A slow reacting substance from rat basophilic leukemia cellsProceedings of the National Academy of Sciences of the United States of America772014-2017(1980) 2.HammarstrÖm, S., Örning, L., and BernstrÖm, K.Metabolism of leukotrienesMolecular and Cellular Biochemistry697-16(1985) 3.Hedqvist, P., DahlÉn, S.E., Gustafsson, L., et al.Biological profile of leukotrienes C4 and D4Acta Physiologica Scandinavica110331-333(1980) 4.Samuelsson, B., DahlÉn, S.E., Lindgren, J.Å., et al.Leukotrienes and lipoxins: Structures, biosynthesis, and biological effectsScience2371171-1176(1987) 5.Lefer, A.M.Leukotrienes as mediators of ischemia and shockBiochem. Pharmacol.35(2)123-127(1986) 6.Drazen, J.M., Austen, K.F., Lewis, R.A., et al.Comparative airway and vascular activities of leukotrienes C-1 and D in vivo and in vitroProceedings of the National Academy of Sciences of the United States of America774354-4358(1980)