ADP mediates release of VEGF from platelets. (A) VEGF concentration in the releasate generated from platelets activated with various concentrations of ADP. (B) Time course of VEGF concentration in the releasate generated from platelets (plts) activated with 25μM ADP. (C) VEGF concentration in releasate generated from platelets resting or activated with ADP alone or pre-incubated with ADP antagonists (A2P5P [A2], A3P5P [A3], and MRS2395 [M]). (D) Immunofluorescence of platelets resting or activated with 10μM or 25μM ADP and labeled with VEGF (green) or endostatin (red). Scale bar is 2μm in size. (E) Immunofluorescence of platelets resting or activated with 25 μM ADP and labeled with endostatin (red) or Fibrinogen (green). (F) Number of granules labeled with VEGF or endostatin in resting platelets or platelets incubated with ADP. Numbers represent average granule counts from immunofluorescence images. (G) Endostatin concentration in releasate generated from resting platelets or platelets activated with 25μM ADP alone or with preincubation with A2. * indicates P < .05.