Aspirin partially restores cGMP generation following arachidonate activation of platelets and enhances the inhibitory effects of NO on thrombin-stimulated platelet activation. (A) Platelet cGMP levels were determined using radioimmunoassay following incubation of washed platelets (± 1 mM aspirin preincubation) with 1.9 μM NO ± 40 μM arachidonate (AA) for 5 minutes, 37°C (n = 3, mean ± SEM; *P < .05, Student unpaired t test).ASAindicates aspirin. (B) Representative trace showing aggregation of washed platelets (control or aspirin treated) at 200 × 109/L in 500 μL Tyrode buffer containing 1 mM CaCl2 at 37°C following addition of 0.4 U/mL thrombin, with and without 1.9 μM NO (added 10 seconds after thrombin). (C) Cumulative data showing the effect of aspirin treatment on the sensitivity of platelets to NO during thrombin-stimulated aggregation (mean ± SEM, n = 3; *P < .05, Student unpaired t test).
