Secondary mediators:
  • Prostaglandins
  • Any of a class of physiologically active substances present in many tissues, with effects such as vasodilation, vasoconstriction, stimulation of intestinal or bronchial smooth muscle, uterine stimulation, and antagonism to hormones influencing lipid metabolism. Prostaglandins are prostanoic acids with side chains of varying degrees of unsaturation and varying degrees of oxidation. Often abbreviated PGA, PGB, PGC, PGD, etc. with numeric subscripts, according to structure.
  • Leukotrienes
    • Products of eicosanoid metabolism (usually, arachidonic acid) with postulated physiologic activity such as mediators of inflammation and roles in allergic reactions; they differ from the related prostaglandins and thromboxanes by not having a central ring; so named because they were originally discovered in association with leukocytes and of three conjugated double bonds; letters A through F identify the first six metabolites isolated, with subscript numbers to indicate the number of double bonds (e.g., leukotriene C4).
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