Inhibition of platelet O$2−$release.

(A) Effect of O$2−$ scavengers on platelet release of O$2−$⁠. N-acetylcysteine (NAC, 1 mM, n = 9) or superoxide dismutase (SOD, 250 U/mL, n = 9) significantly decreased O$2−$ release after PKC stimulation using PMA, whereas boiled SOD was without effect (not shown). When collagen was used as a stimulus, similar results were obtained (6 μg/μL, n = 7 each, 10 minutes after stimulation). (B) Specific NAD(P)H oxidase inhibitors prevent platelet O$2−$ production. A peptide specifically inhibiting the interaction between gp91^phox(or its analogs) and p47^phox (gp91ds-tat, 100 μM) but not its scrambled analog (scrmbl-tat, 100 μM) inhibits platelet O$2−$ production as measured by L-012 chemiluminescence (n = 9, at 10 minutes). (C) Amount of O$2−$ production as measured by cytochrome creduction. Platelet suspensions were stimulated in cytochromec dissolved in PBS, after preincubation with the respective inhibitors when indicated (n = 6, at 10 minutes). Data are shown as mean ± SEM; *, ** significantly different versus control atP < .05 and .01, respectively; #, ##P < .05 and .01 versus stimulus.