A-type natriuretic peptide (atrial natriuretic peptide) is secreted by cardiomyocytes located in the cardiac atria in response to increased stretching of the atrial wall and elevated blood volume. B-type natriuretic peptide (ventricular natriuretic peptide) is secreted by cardiomyocytes located in the heart ventricles. The secretion of the hormone increases due to the stretching of ventricles associated with the elevated ventricular blood volume. Both hormones reduce vascular resistance, decrease central venous pressure and cardiac output, and activate the excretion of sodium in the urine. As a result, the hormones decrease blood pressure.