M04.03.07 Anti-Diuretic Hormone

Anti-diuretic hormone (ADH), also known as arginine vasopressin (AVP), plays a crucial role in the regulation of water balance in the body. It achieves this by acting on specific receptors in the kidney and blood vessels. Its dual role includes the regulation of water reabsorption and vascular tone.

Mechanism of Action

1. Water Reabsorption in Kidneys

• Receptor Involved: V2 receptor.
• Location: Principal cells of the kidney.
• Function: ADH promotes water reabsorption by increasing the permeability of the renal collecting ducts to water, thus conserving water and maintaining extracellular osmolality.

2. Regulation of Vascular Tone

• Receptor Involved: V1 receptor.
• Location: Arterioles.
• Function: ADH induces vasoconstriction, leading to an increase in vascular tone and blood pressure when necessary.

Regulation of ADH Secretion

The secretion of ADH is regulated by two primary factors:

Points to Remember

• ADH regulates water reabsorption through the V2 receptor in the kidney.
• ADH also acts as a vasoconstrictor by binding to the V1 receptor on arterioles.
• Plasma osmolality and blood pressure/volume are the two main regulators of ADH secretion.
• ADH plays a critical role in maintaining extracellular fluid balance and vascular tone.

Bibliography

1. Guyton, A.C., & Hall, J.E. (2016). Textbook of Medical Physiology. Elsevier.
2. Schrier, R.W., & Berl, T. (1975). Mechanisms of action of vasopressin. Kidney International, 8(2), 47–57.
3. Verbalis, J.G. (2003). Disorders of body water homeostasis. Best Practice & Research Clinical Endocrinology & Metabolism, 17(4), 471–503.