Figure 4.

Genetic loss of K_V1.3 impairs neutrophil recruitment in vivo. WT and K_V1.3^−/− mice were stimulated i.s. with TNF-α 2 h prior to intravital microscopy of post-capillary venules of the cremaster muscle and (A) neutrophil rolling and (B) number of adherent neutrophils per vessel surface were analysed [18 (WT) and 18 (K_V1.3^−/−) vessels of n=5 mice per group, unpaired Student’s t-test]. (C) Intravascular shear rates were correlated with respective numbers of adherent cells in WT and K_V1.3^−/− mice [n=18 (WT) and 18 (K_V1.3^−/−) vessels of 5 mice per group, Pearson correlation]. E-selectin, ICAM-1, and CXCL1-coated flow chambers were perfused with murine whole blood from K_V1.3^−/− and WT mice and number of (D) rolling and (E) adherent cells FOV⁻¹ were analysed (20–22 flow chambers from n=7 mice per group, unpaired Student’s t-test). (F) TNF-α stimulated cremaster muscles were stained with Giemsa (representative micrographs, scale bar =30 µm, arrows: transmigrated neutrophils) and number of perivascular neutrophils was quantified [25 (WT) and 59 (K_V1.3^−/−) vessels of n=5 mice per group, unpaired Student’s t-test]. (G) Normal saline (NaCl) or TNF-α was injected i.p. into WT and K_V1.3^−/− mice and numbers of recruited neutrophils to the peritoneum were assessed 6 h later (n=5 mice per group, two-way ANOVA, Sidak’s multiple comparison). *P≤0.05, **P≤0.01, data in (A), (B), and (D)–(G) are represented as mean±SEM, in (C) as Pearson correlation, and in (F) as representative images.