Total profiling by GC/NICIMS of the major cyclo-oxygenase products from antigen and leukotriene-challenged guinea-pig lung.

Separation and quantitation of all the major cyclo-oxygenase products in perfused guinea-pig lungs challenged with antigen or leukotrienes C4 and D4 were achieved using a novel combined capillary column gas chromatography/negative ion chemical ionization mass spectrometric (GC/NICIMS) method. In descending order of magnitude, unchallenged lungs released thromboxane B2 (TXB2) plus its pulmonary metabolite (TXDK) greater than 6-keto-PGF1 alpha plus its 13,14-dihydro-15-keto metabolite (K2H1F1 alpha) greater than PGE2 plus PGF2 alpha greater than PGD2; after ovalbumin anaphylaxis there were increases of X 26 in TXB2 plus TXDK, X 28 in PGD2 and histamine (measured fluorometrically) but of only X 3 in 6-keto-PGF1 alpha plus K2H2F1 alpha and PGE2 plus PGF2 alpha. FPL55712 treatment greatly reduced the release of TXB2 and 6-keto-PGF1 alpha and their metabolites (showing this to be a secondary effect mediated by leukotriene action) but did not affect PGD2 output. LTC4 and LTD4 themselves induced the release of TXB2 and TXDK, as did bradykinin, but neither substance caused appreciable PGD2 release. Aside from illustrating the great value of the GC/NICIMS method for simultaneously determining all cyclooxygenase products, the main conclusions are: (i) PGD2 may be an in vitro marker for activation of lung inflammatory cells; (ii) prostacyclin and thromboxanes are actively metabolized in situ in the lung; and (iii) 'pathological subversion' of pulmonary function by anaphylaxis, leukotrienes or bradykinin principally causes thromboxane release from unknown target cells, with a smaller release of prostacyclin which may be compensatory in nature.