Reduced chemokine-induced arrest in cremaster venules of Gnai2-deficient mice in vivo. (A) Number of adherent cells (normalized to blood neutrophil counts) in cremaster muscle postcapillary venules of Gnai2^−/− mice and littermate control mice after intravenous injection of 600 ng CXCL1. Data were recorded and analyzed for 1 minute starting 15 seconds after CXCL1 injection. Data presented are the means plus or minus SEM from 4 mice. (B) Representative pictures of cremaster muscle postcapillary venules of Gnai2^+/+ and Gnai2^−/− mice before and 1 minute after CXCL1 injection (leukocytes are circuited: rolling leukocytes, · · ·; arrested leukocytes, —). Scale bar equals 10 μm. (C-D) Adherent leukocytes in postcapillary venules of Gnai2^−/− mice (D) or littermate control mice (C) after injection of CXCL1. Each line represents the number of adherent leukocytes per square millimeter in 1 venule of 1 mouse after CXCL1 injection. Data presented as means plus or minus SEM from 4 mice. ^#P < .05.