Effects of coadministration of HU and BAY73-6691 on leukocyte recruitment in TNF-α–treated SCD mice. (A) Leukocyte rolling; (B) leukocyte rolling velocity (velocity of each leukocyte observed; n = 64-82 venules from 3-4 mice per group); (C) leukocyte adhesion, and (D) leukocyte extravasation (n = 5-7 mice per group for A-C-D). (E) Plasma cGMP levels at the time of death/sacrifice as determined by ELISA (n = 5-6 mice per group; *P < .05, **P < .01, ***P < .001). (F) Representative images of SCD mice venules at 180 minutes after TNF-α stimulation. Black stars indicate adherent leukocytes; white arrowheads, RBCs; and white arrow, RBC-WBC interaction. The longer white arrow indicates the direction of blood flow. Scale bar: 10 μm.