Enhanced thromboxane B2 release from challenged guinea pig lung after oxygen exposure

The effects of exposure to 100% oxygen (O2) on the release of thromboxane B2 (TXB2) and prostaglandins (PG) from guinea pig lungs during anaphylaxis were studied. Lungs from sensitized guinea pigs were isolated, perfused, and challenged. Serologic examination of the perfusate showed that larger amounts of TXB2, 6-keto-PGF1 alpha, PGE2, and PGF2 alpha were released from the lungs of animals previously exposed to 100% O2 for 72 h. Conversely, these lungs released smaller amounts of 13, 14-dihydro-15-keto-PGF2 alpha. Histamine release, measured spectrofluorometrically, was unchanged. 15-hydroxyprostaglandin dehydrogenase (PGDH) was inhibited by 83% after O2 exposure, as measured by an in vitro enzyme assay. These results suggested that the reported enhancement of systemic anaphylaxis in the guinea pig in vivo after exposure to oxidant gases may be due in part to inhibition of pulmonary PGDH resulting in increased half-lives of primary PG and TX released from the lung.