ANF is commonly known as Atrial Natriuretic Factor.
ANF is a hormone produced by the walls of the atria of the heart in response to an increase in blood volume and pressure. It increases sodium excretion and decreases blood pressure.
ANF inhibits release of renin from juxta-glomerular apparatus (JGA) and thereby, inhibits NaCl reabsorption by the collecting duct and reduces aldosterone release from the adrenal gland.
Function The function of counter current mechanism is to concentrate NaCL in the intestitial fluid and thereby cause water to diffuse out of the collecting tubules and ducts and concentrate the urine.