Figure 4.

Down-regulation of NOS III mRNA by dexamethasone and reversal of the effect by the glucocorticoid receptor antagonist mifepristone (Mife) in endothelial cells. a shows an autoradiograph of a representative gel of an RNase protection experiment. RNase protection analyses were performed by using antisense RNA probes to human NOS III and β-actin (for standardization) and RNA from EA.hy 926 cells incubated with 0.1 or 1 μM dexamethasone, 1 or 10 μM mifepristone, or a combination of both. T, tRNA control; N, undigested NOS III antisense probe; A, undigested β-actin antisense probe; M, molecular size marker (pGl₂-Basic, restricted with HinfI). The gel is representative of three similar experiments. b shows the down-regulation of NOS III mRNA in three types of endothelial cells: EA.hy 926 cells (●), human umbilical vein endothelial cells (HUVEC, ■), and bovine aortic endothelial cells (BAEC, ▴, using bovine antisense RNA probes). The cells either were left untreated [control cells (Co)] or were incubated with dexamethasone (10 nM to 1 μM) for 18 h. Values represent means ± SEM. Asterisks indicate significant differences from untreated cells (*, P < 0.05; **, P < 0.01; ***, P < 0.001 by ANOVA and Fisher’s PLSD test).