Figure 2.

Inhibition of COX activity by postincubation with γT and γ-CEHC in COX-2-preinduced A549 cells. A549 cells were pretreated with IL-1β (10 ng/ml) for 24 h. (A) Cells were washed and incubated with fresh medium containing vehicle or γ-CEHC for 1 h. AA at final concentrations of 5 or 15 μM was added and incubated at 37°C for 10 min. (B) For γT, the postincubation period was extended to 24 h. Medium was then removed and replaced with a fresh one containing 10 or 30 μM AA at 37°C for 10 min. (C) Cells were postincubated with γT (10 μM) for 1, 8, or 24 h and COX-2 activity was measured as described in B. All reactions were stopped by the addition of 0.5 mM aspirin and PGE₂ in the medium was measured. COX activity (%) is expressed as the ratio of PGE₂ produced in the presence of γT or γ-CEHC to that with vehicle alone. Numbers within brackets indicate the final concentrations of AA. *, P < 0.05 and **, P < 0.01, control vs. tocopherol supplementation.