Fig. 6. MCA Kir2.1 channels are critical components of FIV. A) FIV curves produced by exposing MCAs from WT and Kir2.1^+/- mice to intraluminal flow via the pressure gradient method. Vasodilation is shown as the percent dilation to baseline diameters recorded at physiological pressure (~44 mm Hg) after pre-constriction with ET-1 (120-200 pM) to ~50% of baseline. BaCl₂ (30 µM) is used to block Kir channels and reduce FIV as previously reported [10]. B) Dilations to Δ100 cm H2O intraluminal flow reveal 1) significant inhibition of FIV by Ba²⁺ in WT MCA (*p<0.05; repeated measures 2-way ANOVA) and 2) a significant difference in FIV between WT and Kir2.1+/-(*p<0.05; 2 way-ANOVA). No effect of Ba²⁺ was observed in Kir2.1^+/- MCA.