Effects of dexamethasone on angiotensin II-induced changes of monolayer permeability and F-actin distribution in glomerular endothelial cells.

The aim of this study was to investigate the changes in monolayer permeability and F-actin distribution caused by angiotensin II (Ang II)-induced injury in glomerular endothelial cells (GENCs) and the effects of dexamethasone on these changes. GENCs isolated and cultured from Wistar rats were used to examine the changes in monolayer permeability and F-actin distribution induced by Ang II. GENC permeability was evaluated by measuring the diffusion of biotin-conjugated bovine serum albumin (biotin-BSA) across a cell monolayer. The expression levels and distribution of F-actin were assessed by flow cytometry. The biotin-BSA concentrations were measured by capture enzyme-linked immunosorbent assay. Ang II at a concentration of 10 mg/l increased the permeability of the GENC monolayer at 6 h and 12 h (P<0.05 and P<0.01, respectively) and caused F-actin depolymerisation at 6 h and 12 h (P<0.01). The two effects attributed to Ang II were significantly inhibited by dexamethasone treatment (P<0.01). The increased permeability of the GENC monolayer induced by Ang II was significantly correlated with the depolymerisation of F-actin. Dexamethasone abrogated the Ang II-mediated damage to GENCs indicating that it may play an important role in protecting GENCs from injury.