KRIT1 protein haploinsufficiency increases ROCK-mediated vascular leak in vivo. (A) Krit1^+/− mice have one-half the amount of KRIT1 protein in lung and brain as Krit1^+/+ mice. 1, control mouse IgG IP; 2, Krit1^+/+ lung; 3, Krit1^+/+ brain; 4, Krit1^+/− lung; 5, Krit1^+/− brain lysates. (B) Densitometry of blots in A shows a 50% reduction in KRIT1 in Krit1^+/− lysates. Error bars are means ± SE (n = 3). *, P < 0.03 compared with Krit1^+/+. (C) Krit1^+/− mice had significantly greater basal and LPS-induced Evan’s blue dye leak in brain. Error bars are means and SE of n = 6 mice. *, P < 0.01; **, P < 0.04 compared with vehicle-treated Krit1^+/+ mice. Fasudil reduced leak in the Krit1^+/− mice. (D) Lungs were collected from animals treated as in C and evaluated for dye extravasation. Basal and LPS-induced lung leak were also reversed by fasudil treatment. Error bars are means ± SE (n = 6). *, P < 0.01; **, P < 0.03 compared with Krit1^+/+. (E) Brain edema (difference in wet weight vs. dry weight) was also tested under the same conditions. Brains were weighed, desiccated, and reweighed. Means and SE of data from six animals are shown. Brain edema was increased in Krit1^+/− mice and was reduced by fasudil treatment. Error bars are means ± SE (n = 6). *, P < 0.01 compared with Krit1^+/+. (F) Krit1^+/− mice also had increased pulmonary edema, which was diminished by fasudil treatment. Error bars are means ± SE (n = 6). *, P < 0.01 compared with Krit1^+/+.