Signalling pathways of exendin‐4‐induced vasodilation. (a, d, g, and j) Images depict the effect of inhibitors on exendin‐4‐dilated capillaries. (b, e, h, and k) Percentage change in retinal capillary diameter. (c, f, i, and l) Percentage change in pericyte width in the corresponding area. (a–c) Exendin‐9–39‐attenuated, exendin‐4‐induced vasodilation. (d–f) l‐NAME inhibits exendin‐4‐induced vasodilation. (g–i) ODQ‐reduced exendin‐4‐induced relaxation of capillaries. (j–l) Indomethacin does not inhibit exendin‐4‐induced vasodilation. The red lines indicate the lumen diameter. The yellow arrow indicates the pericyte soma. Scale bar: 10 μm. Randomized block ANOVA followed by an LSD test (N was indicated in each column of the graph). *
P < 0.05, significantly different as indicated. CSF, artificial CSF; NA, noradrenaline; EX‐4, exendin‐4; EX‐9–39, exendin‐9–39; INDO, indomethacin. (m) CHAPS abolishes exendin‐4‐induced vasodilation. (n) Linear regression analysis for correlation between capillary diameter and change in pericyte width (n = 69 pairs)