Hydrogen sulfide (H(2)S) and nitric oxide (NO) are endogenously synthesized from l-cysteine and l-arginine, respectively. They might constitute a cooperative network to regulate their effects. In this study, we investigated whether H(2)S could affect NO production in rat vascular smooth muscle cells (VSMCs) stimulated with interleukin-1beta (IL-1beta). Although H(2)S by itself showed no effect on NO production, it augmented IL-beta-induced NO production and this effect was associated with increased expression of inducible NO synthase (iNOS) and activation of nuclear factor (NF)-kappaB. IL-1Beta activated the extracellular signal-regulated kinase 1/2 (ERK1/2), and this activation was also enhanced by H(2)S. Inhibition of ERK1/2 activation by the selective inhibitor U0126 inhibited IL-1beta-induced NF-kappaB activation, iNOS expression, and NO production either in the absence or presence of H(2)S. Our findings suggest that H(2)S enhances NO production and iNOS expression by potentiating IL-1beta-induced NF-kappaB activation through a mechanism involving ERK1/2 signaling cascade in rat VSMCs.