Inhibition of ADMA metabolism in cells from DDAHI heterozygous (HT) knockout mice affects endothelial permeability (A), nitrite levels (B), Rac1 activity (C), and p-Ser239 VASP levels (D). Pulmonary microvascular endothelial cells we obtained from HT mice and their wild-type (WT) littermates and used at two to three passages. The cells were left untreated or were treated with ADMA, or overexpressing DDAHI/DDAHIM with or without ADMA. * p < 0.05; ** p < 0.05, comparison with untreated controls from WT mice; # p < 0.05, comparison with HT controls. (A and B) n > 5; (C) n = 4; (D) n = 3.