Fig. 1. Effect of crude PDE I (Sigma) and pure PDE I on [Ca²⁺]_i increase in neutrophils.

Fluo-3 AM-loaded neutrophils were re-suspended in HEPES-PS buffer and plated on 96-well plates at a cell density of 3×10⁶ cells/ml, and then incubated at 37℃ for 10 minutes for cell stabilization. (A) CrudePDE I (100, 300 and 500 µU) was added at 300 s. (B) [Ca²⁺]_i was shown as area under curve (AUC), which was calculated for 300 s (300~600 s). (C) Pure PDE I (100, 300 and 500 µU) was added at 300 s. Changes in [Ca²⁺]_i were expressed as the relative fluorescence intensity of Fluo-3 AM over baseline fluorescence intensity (F/F₀). Data points represent the mean±SEM of more than three independent experiments. ^***p<0.001.