Figure 3.

Involvement of sGC/cGMP pathway in the YC-1-induced increase of COX activity and COX-2 expression in A549 cells. In (a), the cells were pretreated with various concentrations of ODQ (sGC inhibitor) or KT (PKG inhibitor) for 30 min followed by a 12 h YC-1 (50 μM) incubation. The media were then removed, and the COX activity was measured by examining the PGE₂ formation in the presence of 30 μM exogenous arachidonic acid for 30 min. Results are expressed as means±s.e.mean of four independent experiments performed in duplicate. ^*P<0.05 as compared with treatment with YC-1 alone. In (b), the cells were pretreated with 30 μM ODQ or 5 μM KT for 30 min before incubation with YC-1 (50 μM) for 12 h. Immunodetection with COX-2 or α-tubulin specific antibody was performed as described in Methods. The equal loading in each lane was demonstrated by the similar intensities of α-tubulin. Data are representative of three independent experiments, which gave essentially identical results. KT, KT-5823.