Aspirin supplementation inhibits NO consumption by platelets from NM volunteers. Baseline NO consumption following a 14-day NSAID-free washout period of washed platelets was determined as described in “Patients, materials, and methods,” then subjects were randomly assigned to receive either aspirin or placebo as described in “Patients, materials, and methods,” before repeat determinations of platelet NO consumption. (A) Representative trace showing NO consumption by platelets from one donor (i) at baseline, (ii) following aspirin supplementation, (iii) after placebo, with 50 μM arachidonate added at arrow. (B) Cumulative data showing the effect of aspirin supplementation on platelet NO consumption rates (mean ± SEM, n = 5 separate donors; *P < .01, Student unpaired t test). (C) Onset and recovery of inhibition of NO consumption by aspirin. Following a baseline determination of arachidonate-stimulated platelet NO consumption, subjects were administered 75 mg aspirin/day for 3 days. NO consumption was measured daily during and for 3 days after aspirin (mean ± SEM, n = 3 separate donors).