Aggregation of WT and GPV-deficient platelets.
Aggregation of washed platelets from GPV null (−/−) or WT (+/+) mice was initiated by the addition of collagen (Coll) (A), ADP, the thromboxane analog U46619, or arachidonic acid (AA) (B), or thrombin (Thr) (C), in the presence (A, B) or absence (C) of fibrinogen. Washed platelets were prepared from pools of 5 to 7 mice for each genotype. GPV null platelets exposed to decreasing doses of collagen gave a diminished response compared to WT platelets, reflected in an increased lag phase and a reduced amplitude of aggregation (A). Concentrations of collagen that induced half-maximal aggregation of WT and GPV null platelets are indicated as EC50 values. Aggregation responses to ADP, U46619, and arachidonic acid were normal in GPV-deficient platelets (B). GPV null platelets displayed enhanced aggregation in response to low doses of thrombin (C). Tracings are representative of at least 3 separate experiments.
