Aggregation induced by supernatants of collagen-stimulated platelets.

(A) Recruitment measured as aggregation induced by supernatants of activated platelets. Aggregation tracings of WP stimulated with supernatants of differentially activated platelets. WP were stimulated with collagen (6 μg/mL) in the presence or absence of SOD (500 U/mL) and pelleted by centrifugation. The supernatants were collected and immediately transferred to an aggregation cuvette with unstimulated platelets to measure aggregation of these untreated WP. As a background tracing collagen-induced aggregation (6 μg/mL) is shown (gray). (B) Recruitment is inhibited by SOD or DPI. Recruitment measured as aggregation induced by supernatants obtained as described above was significantly inhibited by SOD (500 U/mL) when collagen was used as a stimulus. Boiled SOD was without effect. Similar results were obtained when inhibiting NAD(P)H oxidase using DPI (100 μM, n = 7). *Significantly different versus control (stimulus without SOD or DPI) at P < .05.