Question

How does ANF cause a drop in blood pressure?

Answer 1

Atrial Natriuretic Factor (ANF):

1. Atrial Natriuretic Factor or ANF is a member of a family of peptides that have important roles in regulating blood pressure, most prominently through their activity in the kidneys to promote the excretion of water and sodium.
2. A majority of ANF is synthesized and secreted from cardiac muscle cells, particularly in the atria.
3. Thus, the hormone was named for its source (atrial), major physiologic effect (natriuresis or excretion of sodium), and its peptide nature.

Mechanism of action:

1. ANF can be thought of as an anti-hypertensive hormone and plays a central role in the regulation of blood pressure.
2. ANF is initially synthesized within cardiac myocytes as the prohormone preproANF.
3. The biologically-active peptide ANF is released through a series of proteolytic cleavages and in humans is 28 amino acids in length that contain a disulfide bond between two cysteines.
4. The plasma's half-life is only 2-4 minutes.
5. An atrial stretch, which results from excessively large blood volume in circulation, is the most effective trigger for the production of ANF.
6. Enhancing the removal of water and salt in the urine is the targeted physiological reaction to restore this situation.
7. Diuresis is the process of excreting more water and urine due to increased glomerular filtration and reabsorption inhibition.
8. The inner medullary collecting duct is one of the nephron's several segments where ANF functions to limit sodium absorption.
9. Natriuresis, or the excretion of sodium infiltration in urine, occurs when sodium reabsorption is impeded.
10. The heart's atria continuously release ANF, but any unwarranted mechanical stretching can unhealthily speed up this process.
11. ANF works against renal vasoconstriction and inhibits renin secretion in the kidney by increasing sodium excretion and glomerular filtration rate.
12. With increased salt consumption, ANF in the urine rises, demonstrating its crucial function in natriuresis.
13. Vasoconstriction is resisted by ANF in the cardiovascular system.
14. The ANF has a strong inhibitory effect on aldosterone synthesis in the adrenal gland.
15. ANF has a crucial role in both the acute and chronic volume overload natriuretic response.