The sympathoadrenal system mediates the blood pressure and cardiac effects of human coagulation factor XII-related "new pressor protein".

Objective: To investigate the major cardiovascular effects of human plasma "new pressor protein" (NPP) and how the adrenal medulla contributes to these effects.

Methods: NPP was injected into bioassay rats intravenously, and the effects on blood pressure and cardiac function were investigated. Acute adrenal medullectomy (2MDX), alpha- and beta-adrenergic blockade and plasma catecholamine levels were also used to evaluate the role of the sympathoadrenal system in mediating the NPP effects.