Immunohistochemical staining for HIF-1α and VEGF-A. (A) Staining for HIF-1α and VEGF-A on day 28 after AVF creation of outflow vein from vehicle group. HIF-1α and VEGF-A (+) cells have brown staining (black arrows). Images were captured at ×40 magnification. Right panel shows enlarged view of (+) cells across three different layers (×400 magnifications). (B) Staining for HIF-1α and VEGF-A on day 28 after AVF creation of outflow vein from 1,25 NP group. HIF-1α and VEGF-A (+) cells have brown staining. (C) Semiquantitative analysis shows reduction in HIF-1α (+) cells in 1,25 NP group compared with vehicle group. (D) Semiquantitative analysis shows reduction in VEGF-A (+) cells in 1,25 NP group compared with vehicle group. Each bar represents mean±SEM of n≥4. Nonparametric Mann–Whitney test was performed. *P<0.05, **P<0.01. L, lumen; Ad, adventitia; M, media; and I, intima. Scale bar is 500 µm and 50 µm (panel inset).