Pharmacological inhibition of Kir7.1 attenuates neutrophil chemotaxis in zebrafish. (A) Number of total neutrophils in the zebrafish 3 dpf embryos treated with 50 μM VU590 or DMSO. Each dot represents one fish. n > 20 in each group. Data representative of three independent experiments. (B and C) Representative tracks and (C) speed of zebrafish neutrophil spontaneous migration with VU590 or DMSO treatment using Tg(lyzC:mCherry)pu43. Scale bar: 50 μm. Each track represents one neutrophil. n > 15 neutrophils from 3 fish of each group. (D) Schematic illustration of tail transection and neutrophil recruitment. Green dots represent neutrophils. Neutrophils migrating from CHT to the tail 30 min after injury were counted. (E and F) Representative images and (F) quantification of neutrophils recruited to the ventral fin in embryos with VU590 or DMSO treatment. Neutrophils in the boxed regions are quantified. Scale bar: 50 μm. n > 20 in each group. Data representative of three independent experiments. (G) Schematic illustration of the LTB4-induced neutrophil chemotaxis assay. Red dots represent neutrophils. Neutrophils migrate from CHT to the ventral fin fold in the LTB4 bath. 30 min after injury were counted. (H and I) Representative images and quantification (I) of neutrophils migrating to the ventral fin fold 30 min in an LTB4 bath with VU590 or DMSO treatment. n > 20 in each group. Data representative of three independent experiments. Scale bar: 50 μm. (A, C, F, and I) Results are presented as mean ± SD, Mann–Whitney test. (J) Representative tracks of human PMN chemotaxis toward LTB4 after treatment with DMSO, BaCl₂, KCl, VU590, or ML133 in an under-agarose migration plate coated with collagen IV. The lines represent individual cell trajectories over a 60-min period. (K and L) Quantification of speed and forward migration index (FMI). n > 15 in each group. Data present mean ± SD, representative of three independent experiments. Multiple comparisons and one-way ANOVA.