Probable FAD-dependent amine oxidase secreted by the kidney, which circulates in blood and modulates cardiac function and systemic blood pressure. Degrades catecholamines such as dopamine, norepinephrine and epinephrine in vitro. Lowers blood pressure in vivo by decreasing cardiac contractility and heart rate and preventing a compensatory increase in peripheral vascular tone, suggesting a causal link to the increased plasma catecholamine and heightened cardiovascular risk. High concentrations of catecholamines activate plasma renalase and promotes its secretion and synthesis.