Figure 5.

Effect of an incubation of EA.hy 926 cells with dexamethasone for 36 h on NOS III protein expression and NOS activity. a shows a Western blot analysis using a polyclonal anti-NOS III- and a monoclonal anti-β-tubulin-antibody (for normalization). Combined cytosolic and solubilized particulate protein fractions were prepared from untreated EA.hy 926 cells [control (Co)] and EA.hy 926 cells incubated with dexamethasone (10–1,000 nmol) for 36 h. M, molecular weight marker. The blot shown is representative of four independent experiments with similar results. b shows the effect of a 36-h incubation with dexamethasone on the NO production of EA.hy 926 cells stimulated for 2 min with Ca²⁺ ionophore A23187 (10 μM). NO production was measured by the activation of soluble guanylyl cyclase in RFL-6 reporter cells. cGMP content of the RFL-6 cells after a 2-min incubation was determined by radioimmunoassay. Basal cGMP content of the RFL-6 cells (2.12 ± 0.4 pmol/10⁶ cells) was subtracted from all samples. Data represent means ± SEM of three independent experiments. Asterisks indicate significant differences from untreated cells (***, P < 0.001 by ANOVA and Fisher’s PLSD test).