Evidence against the formation of 13,14‐dihydro‐15‐keto‐prostaglandin F2α following inhalation of prostaglandin D2 in man

Abstract

1 There is evidence that an important step in the metabolism of prostaglandin D₂ (PGD₂) involves 11-keto-reduction and that such a conversion might account for the reported increase in plasma concentrations of 13,14-dihydro-15-keto-PGF_2α in allergic asthmatic subjects challenged with inhaled allergen. 2 Plasma concentrations of immunoreactive 13,14-dihydro-15-keto-PGF_2α were measured by specific radioimmunoassay both before and after inhalation of PGD₂ and PGF_2α in 7 normal and 7 asthmatic men. 3 In both groups of subjects, PGF_2α produced an approximate two fold increase in plasma concentrations of 13,14-dihydro-15-keto-PGF_2α that was maximal 5–7 min after inhalation. There was no significant difference in response between the normal and asthmatic subjects. 4 In contrast, PGD₂ failed to produce a change in plasma 13,14-dihydro-15-keto-PGF_2α concentration in either group. 5 These results provide evidence that the conversion of PGD₂ to PGF_2α with subsequent metabolism to 13,14-dihydro-15-keto-PGF_2α is unlikely to occur when PGD₂ is released from mast cells in the airways.