PKA promotes endothelial cell-cell adhesion in vivo and suppresses vascular leak. (A) Images of mouse ears after Evans Blue dye leakage at 1× and 10× following stimulation by VEGF and treatment with vehicle control (2% DMSO) or forskolin. (B) Quantification of vascular leak by dye extraction and measurement of Evans Blue absorbance at 600 nm ± SEM after intradermal injection of VEGF or saline and treatment with 2% DMSO or 100μM forskolin, n = 10, **P = .00 001, *P = .013, in comparison to saline. (C) Brightfield images at 200× and 1000× (inset) of silver nitrate–stained aortas that were stimulated with VEGF and treated with DMSO or forskolin. Silver nitrate foci at endothelial cell junctions are indicated by white arrowheads or by black arrowheads in the inset. Bands of vascular smooth muscle surrounding the endothelium are also outlined. (D) Average number ± SEM of silver nitrate foci/cell in 200× microscopic fields in DMSO and forskolin treated vessels, n = 6, *P = .00 001. (E) Brightfield images at 600× and 200× (inset) of silver nitrate stained carotid arteries that were stimulated with VEGF and treated with DMSO or forskolin. Arrowheads indicate areas of silver nitrate stain. (F) Average area of silver nitrate staining ± SEM in 600× microscopic fields in DMSO and forskolin treated vessels, n = 6, *P = .004.