Increased platelet accumulation at the site of vascular injury in Grk5^−/− mice. (A) Platelet accumulation was visualized by CD41 staining after laser injuries in cremaster muscle arterioles and recorded using confocal intravital fluorescence microscopy. (B) Area under CD41 vs time curve. (C) Peak of the CD41⁺ area at 180 seconds after injury. Bar graph (D) and dot plots (E) showing CD41 deposition at 180 seconds after injury. All data are mean ± SEM; 36 injuries in 3 WT mice and 36 injuries in 4 Grk5^−/− mice. (F) Representative images of anti-GPIX–labeled thrombi in lungs harvested from WT and Grk5^−/− mice. Images were acquired using the Odyssey LiCor imaging system. (G) Thrombosis score, representing the mean thrombus area and number of thrombi, for 8 WT mice vs 8 Grk5^−/− mice. Group means were compared using the Student t test; P ≤ .05 was considered statistically significant. AUC, area under the curve; NS, not significant.