Fig. 5.

NO inhibits platelet adherence and aggregation in vivo. (A) Platelet rolling. Wild-type mice were anesthetized and injected with calcein-AM-labeled platelets from wild-type (WT) or eNOS^-/- mice. The mesentery was externalized, and venules 120–150 μm in diameter were treated with 250 mM FeCl₃. Platelet rolling on venules was imaged with a digital fluorescent camera (n = 7–8 ± SEM). (B) Digital fluorescence images of platelet rolling. Wild-type mice were anesthetized and injected with calcein-AM-labeled platelets from wild-type or eNOS^-/- mice. The mesentery was externalized, and venules 120–150 μm in diameter were treated with 250 mM FeCl₃. Platelet rolling on venules was imaged with a digital fluorescent camera 0, 1, 6, and 10 min after FeCl₃ treatment. (Representative images from n = 7–8.) (C) Thrombosis. Mice were injected with labeled platelets as above. The mesentery was externalized, and arterioles 50–80 μm in diameter were treated with 500 mM FeCl₃. The time to formation of the first thrombus >10 μm in size was recorded (n = 5 ± SD). (D) Digital fluorescent images of thrombosis. Wild-type and eNOS^-/- mice were injected with labeled wild-type platelets, arterioles were treated with FeCl₃ as above, and a digital fluorescent camera was used to visualize formation of the first thrombus >10 μm in size. (E) Exocytosis in shed platelets. The distal 3 mm of wild-type and eNOS^-/- mice tails were amputated, and shed blood was collected. Platelets were analyzed for surface P-selectin expression by FACS. Shed platelets from eNOS^-/- have increased exocytosis as measured by P-selectin expression compared with WT mice. (n = 3 ± SD, *, P < 0.002 for WT vs. eNOS^-/-.)