Atrial diuretic peptide (ANP): role in controlling renal excretion
Changes in ANP levels can help minimize changes in blood volume during various episodes, such as increased salt and water levels.
Other topics have discussed the role of sodium and water retention hormones in controlling extracellular fluid volume. However, a number of different sodium diuretic hormones can also contribute to volume regulation. One of the most important of them is a peptide called atrial diuretic sodium peptide (ANP), released by atrial muscle fibres. This peptide-releasing stimulus appears to increase atrial tension, possibly due to excess blood flow. Once released by the atrium, the ANP enters the circulation and acts in the kidneys to cause a small increase in glomerular filtration rate (GFR) and a decrease in sodium reabsorption through the manifold. These combined activities of ANP lead to increased excretion of salt and water, helping to replenish excess blood.
Changes in ANP levels can help minimize changes in blood volume during various episodes, such as increased salt and water levels. However, overproduction of ANP or even a complete lack of ANP does not cause large changes in blood volume as these effects can be easily overcome by small changes in blood pressure, acting through diuretic sodium pressure. For example, infusion of large amounts of initial ANP increases the amount of salt and water in the urine and causes a slight decrease in blood volume. In less than 24 hours, this effect is corrected by slightly lowering blood pressure to return urine to normal, even though the ANP continues to be in excess.