Our present study aimed to characterize the effects of lipopolysaccharide (LPS) on the expression of the bradykinin B-2-receptor in the mouse heart, which may have a role in cardiac depression during sepsis. We found that LPS induced the up-regulation of B-2-receptor mRNA in the heart in vivo and in cultured cardiac myocytes in vitro. Like LPS, tumor necrosis factor-alpha (TNF-alpha) but not interleukin (IL)-1-beta, IL-6 or endothelin-1 stimulated B-2-receptor expression in cultured myocytes. The effect of LPS on the expression of B2-receptor mRNA was also mimicked in cardiac myocytes by Ang II via Ang II type 1 (AT(1)-) receptor. Losartan, an AT(1)-receptor antagonist, inhibited about 50% of the LPS-induced up-regulation of B-2-receptor mRNA in the heart in vivo and in cultured cardiac myocytes in vitro. Furthermore, the up-regulation of B-2-receptor mRNA by either LPS or Ang II in cultured myocytes was abolished by anti-TNF-alpha antibody. These results suggest that the up-regulation of cardiac B-2-receptor expression by LPS is mediated through TNF-alpha, which is produced in the myocardium by two different mechanisms in an AT(1)-receptor-dependent and independent manners, implying the role of the cardiac kallikrein-kinin system in the development of cardiac dysfunction during sepsis.