Exogenous TSP1 reverses the delay of platelet aggregation by NO. Washed human platelets in Tyrode buffer (2 × 105 platelets/μL) were incubated in the presence of thrombin (0.2 U/mL) and exogenous NO (DEA/NO 10 μM) for 5 minutes under high shear (1200 rpm, A,B) or static (C) conditions and absorbance was recorded. In other experiments, fresh, washed human platelets in Tyrode buffer (500 μL) were treated with TSP1 (2.2 nM) (D) or the indicated concentrations of TSP1 or fibronectin (E) and DEA/NO (10 μM) for 5 minutes and lysed, and cGMP was determined via immunoassay. Platelets in PRP were treated with TSP1 (2.2 nM) for 15 minutes followed by NO (DEA/NO 10 μM) for 5 minutes and lysed, and cGMP was determined via immunoassay (F). Data presented are representative of at least 3 experiments (A-C). Results are the mean (± SD) of at least 3 experiments (D,F).
