The Effect of Ozone Exposure on Rat Alveolar Macrophage Arachidonic Acid Metabolism

Abstract

Rat alveolar macrophages were prelabeled with ³H-arachidonic acid (³H-AA) and exposed to air or O₃ (0.1–1.0 ppm) in vitro for 2 h. Alveolar macrophages released 3.6-fold more tritium at the 1.0 ppm exposure concentration compared with air-exposed macrophages. A significantly increased production of several ³H-AA metabolites, including 6-keto-PGF_1aL, thromboxane B₂, 12-hydroxy-5,8,10-heptadecatrienoic acid, prostaglan-dins E₂ and D₂, leukotrienes B₄ and D₄, and 15-hydroxyeicosatetraenoic acid was formed by macrophages exposed to 1.0 ppm O₃ compared with air-exposed macrophages as determined by high performance liquid chromatography (HPLC) analysis. O₃ exposure did not alter macrophage ³H-AA metabolism in response to calcium ionophore A23187. The largest tritiated peak observed in the HPLC chromatograms of 0₃-exposed cells was a polar complex of products that contained various phospholipids and neutral lipids (including diacylglycerol) and possibly degradation products of ³H-AA and some of its metabolites. These changes in macrophage arachidonic acid metabolism may play an important role in the lung response to O₃ exposure in vivo.