Hormone produced in the kidneys that appears to be important for maintaining cardio-renal homeostasis. Mediates vasodilation, natriuresis and diuresis primarily in the renal system, in order to maintain the extracellular fluid volume and control the fluid-electrolyte balance. Specifically binds and stimulates cGMP production by renal transmembrane receptors, likely NPR1. Urodilatin not ANP, may be the natriuretic peptide responsible for the regulation of sodium and water homeostasis in the kidney