Identification of 13,14‐dihydro‐15‐oxo‐prostaglandin F_2α in the circulation during infusions of bradykinin and prostaglandin E₂ in man

Bradykinin, prostaglandin E₂ (PGE₂), PGD₂ and vehicle (saline) were each administered intravenously on separate occasions to 6 healthy men for a period of 60 min. 13,14‐Dihydro‐15‐oxo‐PGF_2α was identified in plasma samples obtained during intravenous infusions of bradykinin and PGE₂ but not during infusions of PGD₂ or saline. The structure of this metabolite was verified by comparison of three different derivatives with authentic standards, using gas chromatography/electron capture mass spectrometry. Bradykinin increased plasma concentrations of 13,14‐dihydro‐15‐oxo‐PGF_2α from baseline values in the range < 5–10 pg ml⁻¹ to 28–403 pg ml⁻¹. PGE₂ increased plasma concentrations of 13,14‐dihydro‐15‐oxo‐PGF_2α from baseline values in the range < 5–17 pg ml⁻¹ to 160–603 pg ml⁻¹. Neither PGD₂ nor the vehicle affected 13,14‐dihydro‐15‐oxo‐PGF_2α concentrations. We conclude that bradykinin‐stimulated 13,14‐dihydro‐15‐oxo‐PGF_2α may be derived from PGE₂ or PGF_2α. The possibility that these prostaglandins are synthesized by stimulation of microvascular endothelium during bradykinin infusion is discussed. 1987 British Pharmacological Society