Objectives: Adrenomedullin (AM) is a hypotensive and vasodilative peptide. It has been reported that AM plays several biological roles in cardiovascular and endocrine systems, however, effects on the blood coagulation system have not been examined. In this study, we examined its effect on tissue factor pathway inhibitor (TFPI), which is a potent inhibitor of tissue factor/factor VIIa complex-induced coagulation cascade, and is synthesized and constitutively secreted by endothelial cells (ECs). The aim of this study was to elucidate the effects of AM on release and production of TFPI in ECs.
Methods: Cultured human aortic ECs were incubated with AM (10(-14)-10(-6) M), and the antigen levels and activity of the free and total form of TFPI after AM exposure were measured in culture media using ELISA. Furthermore, receptor interaction and cellular signaling of AM were investigated.
Results: AM augmented TFPI release and production in a dose-dependent manner. The effect on TFPI production was inhibited by AM receptor antagonist (AM22-52), the monoclonal antibody against C-terminal region of AM, MAPKK inhibitor, and cAMP antagonist.
Conclusion: These findings indicate that AM might play an important role in the modulation of anticoagulant properties in blood circulation.