Platelet accumulation in VAMP-8^−/− mice after laser-induced injury of cremaster arterioles. (A) Platelet accumulation was imaged at the indicated time intervals after injury in both wild-type (WT) and VAMP-8–deficient (VAMP-8^−/−) mice. (B) Median integrated platelet fluorescence intensity was plotted at each second for 180 seconds after laser injury in VAMP-8^−/− mice. (C) At 30 seconds, median platelet accumulation in VAMP-8^−/− mice was 4% of WT (P = .01). There was a trend toward a decrease in maximal thrombus size in VAMP-8^−/− mice compared with WT mice, but the difference was not statistically significant (74% of WT; P = .061). By 180 seconds, median platelet accumulation in VAMP-8^−/− mice was 28% of WT mice (P = .01).