Figure 6. NAC inhibits ADP- and collagen-induced platelet aggregation.

Aliquots of citrated platelet-rich plasma were mixed with NAC-containing buffer (NAC concentration: 0, 1, 2, 4, 8, 16, or 32 mM) immediately before addition of agonist. Platelet aggregation was monitored for 5 minutes. Maximum aggregations at the different concentrations of NAC were expressed as a percentage of agonist-induced aggregation in the absence of NAC. NAC inhibited platelet aggregation in a concentration-dependent manner, but the extent of inhibition varied among donors. The inhibitory effects of NAC were observed using 10 and 20 μM ADP or 5 and 10 μg/ml of collagen. Platelet aggregation induced by 20 μM ADP and 10 μg/ml of collagen are shown. Data were obtained from 4 donors, shown using different symbols. Linear regression methods were used to model the dose-response relationships between NAC and platelet aggregation. The equation derived for part A was y = (–18) log₂ (×) + 109.8 (SEM for slope and intercept were ± 1.4 and ± 8.9, respectively); in part B, the equation was y = (–13.4) log₂ (×) + 112.2 (SEM for slope and intercept were ± 1.7 and ± 7.5, respectively). These showed that platelet aggregation induced by either 20 μM ADP or 10 μg/ml collagen decreased as NAC concentration increased.