Bradykinin (BK) B(1) receptors are thought to exert a pivotal role in maintaining and modulating inflammatory processes. They are not normally present under physiological situations but are induced under physiopathological conditions. In isolated human umbilical vein (HUV), a spontaneous BK B(1) receptor up-regulation and sensitization process has been demonstrated. Based on pyrrolidine-dithiocarbamate inhibition, it has been proposed that this phenomenon is dependent on nuclear factor-kappaB (NF-kappaB) activation. The aim of this study was to further evaluate the NF-kappaB pathway involvement on BK B(1) receptor sensitization in isolated HUV, using several pharmacological tools. In 5-h incubated rings, either the I-kappaB kinase inhibitor 3-(4-methylphenylsulfonyl)-2-propenenitrile (Bay 11-7082) or the proteasome activity inhibitor Z-Leu-Leu-Leu-CHO (MG-132) inhibited the development of the BK B(1) receptor-sensitized contractile responses. Furthermore, pro-inflammatory cytokine interleukin-6 (IL-6) produced a leftward shift of the concentration-response curve to the BK B(1) receptor agonist, whereas anti-inflammatory cytokines interleukin-4 (IL-4) and tumor growth factor-beta1 (TGF-beta1) produced a rightward shift of the responses to des-Arg(9)-BK in our preparations. Taken together, these results point to NF-kappaB as a key intermediary in the activation of the expression of BK B(1) receptor-sensitized responses in HUV and support the role of inflammatory mediators in the modulation of this process.