Acute renal failure (ARF) is frequently associated with polyuria and urine concentration defects and it is a severe complication of sepsis because it increases the mortality rate. Inhibition of nuclear factor-kappaB (NF-B) activation has been suggested to provide a useful strategy for the treatment of septic shock. However, the impact on sepsis-induced ARF is still unclear. Therefore, we examined the effect of pyrrolidine dithiocarbamate (PDTC) and of small interfering RNA (siRNA) silencing NF-B p50/p105 on sepsis-induced downregulation of vasopressin V₂ receptors and aquaporin (AQP)-2 channels using a cecal ligation and puncture (CLP) mouse model. CLP caused a time-dependent downregulation of renal vasopressin V₂ receptor and of aquaporin-2 (AQP2) expression without alterations in plasma vasopressin levels. Renal activation of NF-B in response to CLP was attenuated by PDTC pretreatment, which also attenuated the downregulation of V₂ receptor and AQP2 expression. Furthermore, a strong nuclear staining for the NF-B p50 subunit throughout the whole kidney in response to CLP was observed. siRNA against NF-B p50 attenuated the CLP-induced nuclear translocation of the p50 subunit and the CLP-induced downregulation of V₂ receptor and AQP2 expression. Additionally, PDTC and siRNA pretreatment inhibited the CLP-induced increase in renal TNF- and IL-1 concentration and in NOS-2 mRNA abundance. Moreover, PDTC and siRNA pretreatment ameliorated CLP-induced hypotension and acute renal failure. Our findings suggest that NF-B activation is of importance for the downregulation of aquaporin-2 channel and vasopressin V₂ receptor expression during sepsis. In addition, our data indicate that NF-B inhibition ameliorates sepsis-induced acute renal failure.