Figure 2. Tempol inhibits neutrophil and platelet pro-hemostatic functions.

Inhibition of superoxide production. HL-60 cells were incubated with Tempol (0, 0.3, and 1 mM) followed by addition of fMLP (1 µM). Superoxide production was detected with Diogenes reagents. B, Inhibition of H₂O₂ production. HL-60 cells were incubated with Tempol (0, 0.3, and 1 mM) followed by addition of fMLP (1 µM). H₂O₂ production was detected with luminol/HRP-based chemiluminescence assay. C, Effects on platelet aggregation. Platelet-rich plasma was incubated with Tempol (0, 1, and 3 mM) for three hours and activated with collagen (1 µg/mL). A representative tracing is shown (similar results obtained with two other donors). D, Effects on platelet secretion. Platelets were activated as above, and ATP was determined by luminescence using Luciferin-luciferase reagent. Experiments were performed in triplicate or quadruplicate. *, P≤0.05 (analysis of variance, Bonferroni post-test).