The role of prostanoids in ozone-induced changes in airway responsiveness: receptor activation-specific prostanoid release

We studied the effect of in vivo ozone exposure (3 ppm, 2 h) on methacholine- and histamine-induced guinea pig tracheal smooth muscle contractions in vitro and the role of cyclooxygenase products in this process. After exposure to ozone, methacholine stimulation showed a functional hyperreactivity, whereas after stimulation with histamine a hyporeactivity was observed. These effects could be explained by the release of prostanoids. In a control situation an increase in PGF 2 α , PGE 2 and PGD 2 release is observed after stimulation of the histaminergic receptor system. After ozone exposure the release of prostanoids was also enhanced (unstimulated, PGF 2 α and TxB 2; histamine, PGF 2 α , PGE 2; methacholine, PGF 2 α , TxB 2, 6-kPGF 1 α , PGE 2). This study shows that the prostanoid release is strongly dependent on the receptor system stimulated to induce smooth muscle contraction and the importance of prostanoids in ozone-induced changes in guinea pig tracheal smooth muscle reactivity.