Effect of hGPVI-Fc or anti-GPVI antibodies on platelet adhesion in vivo. (A) Mice received the indicated amounts of hGPVI-Fc intravenously, and blood was drawn at the indicated time points. The plasma concentration of hGPVI-Fc was determined by ELISA. Results are given as mean ± SD from triplicate readings of 3 individual experiments. (B-D) Intravital microscopy. Mice received the indicated amounts of hGPVI-Fc, hGPVI-Fc*, or vehicle intravenously, and platelet-vessel wall interactions after vascular injury were examined by in vivo fluorescence microscopy of the common carotid artery in situ. In parallel, JAQ1-treated (2 mg/kg) and FcRγ–/– mice were tested. (B) The photomicrographs show representative in vivo fluorescence microscopy images 3 minutes after injury in mice treated with vehicle, hGPVI-Fc (4 mg/kg), hGPVI-Fc* (4 mg/kg), or JAQ1 (2 mg/kg). Platelet adhesion (C) and aggregate formation (D) shown as mean ± SD of 7 experiments per group.