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