Illustration of a dendroaspis natriuretic peptide (DNP, blue spheres) bound to an atrial natriuretic peptide receptor. DNP is found in the venom of the green mamba snake (Dendroaspis angusticeps). Natriuretic peptides are a family of proteins that regulate the cardiovascular system by promoting the excretion of sodium through the kidneys (natriuresis) and dilating blood vessels (vasodilation) to lower blood pressure. Atrial natriuretic peptide receptors are found in the upper chambers (atria) of the heart.