Fig. 1.

Ascorbate loading decreases endothelial barrier permeability and increases cell surface area. A: confluent human umbilical vein endothelial cells (HUVECs) were incubated for 90 min with the indicated concentrations of ascorbate or dehydroascorbic acid (DHA) and taken for assay of ascorbate as described under materials and methods. Results are from 4 plates with each form of ascorbate ± SE. B: HUVECs grown several days past confluence on Transwell filters were treated in the upper or luminal chamber with the indicated concentrations of ascorbate or DHA for 30 min before the 60-min radiolabeled inulin transfer assay. Results are shown from 5 experiments with DHA and 6 with ascorbate ± SE. *P < 0.05, compared with the respective sample not treated with ascorbate or DHA. C: confluent HUVECs on fibronectin-coated glass coverslips were treated overnight with 150 μM DHA, fixed, and stained for VE-cadherin to define cell boundaries as described in materials and methods. Cells were visualized at ×20 as described in materials and methods. Arrows indicate gaps between cells. D: quantification of cell size ± SD from 355 control and 232 DHA-treated cells by a second blinded observer. *P < 0.05, compared with control by nonpaired Student's t-testing.