The inhibitory effect of ADP scavengers on platelet aggregation induced by FcγRIIA cross-linking or by HIT sera is reversed by epinephrine.

Human platelet suspensions were preincubated (1 minute, 37°C) with 500-mol/L A3P5PS, 0.1 μmol/L AR-C69931MX, 1-IU/mL apyrase, 50-μmol/L ATPγS, 5-mmol/L CP, and 40-IU/mL CPK or CP-CPK plus 0.5-μmol/L or 1-mol/L epinephrine and then stimulated by FcγRIIA cross-linking (A) or by 80 μL of sera from HIT patients (B) as indicated in “Materials and methods.” Aggregation was assessed using a Chrono-Log dual-channel aggregometer with stirring at 900 rev/min (5 × 10⁸ cells/mL).