Aldosterone inhibits nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 β

We investigated the effects of aldosterone on nitric oxide (NO) synthesis in vascular smooth muscle cells. We measured the production of nitrite, a stable metabolite of NO, and the expression of inducible NO synthase mRNA and protein in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1β (10 ng/ml) for 24 h caused a significant increase in nitrite generation. The interleukin-1β-induced nitrite production by vascular smooth muscle cells was significantly inhibited by aldosterone in a dose (10⁻⁹ ∼ 10⁻⁶ M)-dependent manner. Incubation with interleukin-1β for 12 ∼ 24 h caused inducible NO synthase mRNA expression in vascular smooth muscle cells, whereas aldosterone had a suppressive effect on its expression. Aldosterone also decreased interleukin-1β-induced inducible NO synthase protein accumulation. These results indicate that aldosterone inhibits NO synthesis under interleukin-1β-stimulated conditions in vascular smooth muscle cells.