Platelet counts after collagen plus epinephrine infusion. Mice were injected with 600 ng/g collagen plus 60 ng/g epinephrine via tail vein and platelet counts were measured 5 minutes after injection. Symbols represent platelet counts from a single mouse. Bars represent the mean values of 25 mice in each group. Platelet counts of untreated mice were not different among the groups.