Vasopressin is a hormone that regulates osmolality, which is the concentration of dissolved particles, like salts and glucose, in serum, and maintains the volume of water in extracellular fluid. It safeguards cells from abrupt changes in water content, which can disrupt cell function. Vasopressin is produced by special nerve cells called osmoreceptors in the hypothalamus, which are sensitive to changes in serum osmolality. These cells release vasopressin from the posterior pituitary gland, prompting the kidneys to retain water. Vasopressin acts on the cells of the collecting ducts in the kidneys. When these cells are stimulated by vasopressin, water channels open, allowing water to be reabsorbed into the circulation, which decreases urine volume and concentrates its contents.

Where is vasopressin made in the body?

Vasopressin, also known as antidiuretic hormone, is synthesized in the hypothalamus within two pairs of nerve cell clusters called the supraoptic and paraventricular nuclei. From there, vasopressin is incorporated into neurosecretory granules and travels through nerve extensions (axons) to the posterior lobe of the pituitary gland . Upon stimulation, vasopressin is released into the bloodstream, regulating blood pressure and increasing water reabsorption in the kidneys to conserve body water and defend against dehydration. Special nerve cells called osmoreceptors in the hypothalamus are sensitive to changes in serum osmolality, which can trigger the release of vasopressin.

What is the main function of vasopressin?

The primary function of vasopressin is to regulate osmolality, which is the concentration of dissolved particles in the serum, and to maintain the volume of water in extracellular fluid. This regulation is crucial for protecting cells from water content changes that could disrupt their function. Vasopressin is released in response to even small increases in serum osmolality, such as those caused by dehydration. It stimulates water retention in the kidneys by acting on cells in the collecting ducts, which contain receptors linked to water channels called aquaporins. When stimulated, these aquaporins allow water to be reabsorbed into the circulation, concentrating the urine and reducing its volume. Vasopressin is also known as an antidiuretic hormone.

How does vasopressin help the kidneys?

Vasopressin helps the kidneys maintain the volume of water in extracellular fluid by acting on cells in the collecting ducts. These cells contain vasopressin receptors linked to vesicles that have special water channels called aquaporins. When stimulated by vasopressin, aquaporins merge with the cell membrane exposed to urine, which allows water to enter the cells and return to the circulation. As a result, urine volume decreases, the concentration of sodium, chloride, and other substances in the urine increases, and the urine becomes more concentrated.

What happens if the body doesn't have enough vasopressin?

If the body doesn't have enough vasopressin , a pathological endocrine condition known as diabetes insipidus can occur, characterized by excessive thirst and the production of very dilute urine. Vasopressin, or antidiuretic hormone, regulates the kidney’s conservation of water and production of urine. A deficiency of vasopressin secretion (central diabetes insipidus) or a deficiency of vasopressin action in the kidney (nephrogenic diabetes insipidus) can cause diabetes insipidus. This hormone is released from the posterior pituitary gland via activation of the hypothalamus in response to physiological signals.

How is vasopressin's action related to water balance and blood pressure?

Vasopressin, a peptide hormone, is crucial for maintaining water balance and blood pressure. It increases water retention by making kidney tubules more permeable to water, which increases extracellular fluid volume and blood pressure. Vasopressin is released in response to increased extracellular fluid osmolality and decreased blood volume. Osmotic stimuli act on circumventricular organs, while baroreceptors relay volume and pressure information to hypothalamic neurons, triggering vasopressin release. In emergency situations, vasopressin constricts nonessential vascular beds, shunting blood to critical organs like the heart and brain.

vasopressin

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vasopressin

biochemistry

Also known as: ADH, antidiuretic hormone

Written by

Robert D. Utiger

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Last updated

Oct. 1, 2026 •History

Top Questions

What is vasopressin?
Vasopressin is a hormone that regulates osmolality, which is the concentration of dissolved particles, like salts and glucose, in serum, and maintains the volume of water in extracellular fluid. It safeguards cells from abrupt changes in water content, which can disrupt cell function.

Vasopressin is produced by special nerve cells called osmoreceptors in the hypothalamus, which are sensitive to changes in serum osmolality. These cells release vasopressin from the posterior pituitary gland, prompting the kidneys to retain water.

Vasopressin acts on the cells of the collecting ducts in the kidneys. When these cells are stimulated by vasopressin, water channels open, allowing water to be reabsorbed into the circulation, which decreases urine volume and concentrates its contents.
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Where is vasopressin made in the body?
Vasopressin, also known as antidiuretic hormone, is synthesized in the hypothalamus within two pairs of nerve cell clusters called the supraoptic and paraventricular nuclei. From there, vasopressin is incorporated into neurosecretory granules and travels through nerve extensions (axons) to the posterior lobe of the pituitary gland.

Upon stimulation, vasopressin is released into the bloodstream, regulating blood pressure and increasing water reabsorption in the kidneys to conserve body water and defend against dehydration. Special nerve cells called osmoreceptors in the hypothalamus are sensitive to changes in serum osmolality, which can trigger the release of vasopressin.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What is the main function of vasopressin?
The primary function of vasopressin is to regulate osmolality, which is the concentration of dissolved particles in the serum, and to maintain the volume of water in extracellular fluid. This regulation is crucial for protecting cells from water content changes that could disrupt their function.

Vasopressin is released in response to even small increases in serum osmolality, such as those caused by dehydration. It stimulates water retention in the kidneys by acting on cells in the collecting ducts, which contain receptors linked to water channels called aquaporins. When stimulated, these aquaporins allow water to be reabsorbed into the circulation, concentrating the urine and reducing its volume.

Vasopressin is also known as an antidiuretic hormone.
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1. Definition of vasopressin
2. vasopressin
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How does vasopressin help the kidneys?
Vasopressin helps the kidneys maintain the volume of water in extracellular fluid by acting on cells in the collecting ducts. These cells contain vasopressin receptors linked to vesicles that have special water channels called aquaporins. When stimulated by vasopressin, aquaporins merge with the cell membrane exposed to urine, which allows water to enter the cells and return to the circulation. As a result, urine volume decreases, the concentration of sodium, chloride, and other substances in the urine increases, and the urine becomes more concentrated.
1 Britannica Source
1. vasopressin
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What happens if the body doesn't have enough vasopressin?
If the body doesn't have enough vasopressin, a pathological endocrine condition known as diabetes insipidus can occur, characterized by excessive thirst and the production of very dilute urine.

Vasopressin, or antidiuretic hormone, regulates the kidney’s conservation of water and production of urine. A deficiency of vasopressin secretion (central diabetes insipidus) or a deficiency of vasopressin action in the kidney (nephrogenic diabetes insipidus) can cause diabetes insipidus. This hormone is released from the posterior pituitary gland via activation of the hypothalamus in response to physiological signals.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How is vasopressin's action related to water balance and blood pressure?
Vasopressin, a peptide hormone, is crucial for maintaining water balance and blood pressure. It increases water retention by making kidney tubules more permeable to water, which increases extracellular fluid volume and blood pressure.

Vasopressin is released in response to increased extracellular fluid osmolality and decreased blood volume. Osmotic stimuli act on circumventricular organs, while baroreceptors relay volume and pressure information to hypothalamic neurons, triggering vasopressin release. In emergency situations, vasopressin constricts nonessential vascular beds, shunting blood to critical organs like the heart and brain.
2 Britannica Sources
1. vasopressin
2. human nervous system: Vasopressin and cardiovascular regulation
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

vasopressin, hormone that plays a key role in maintaining osmolality (the concentration of dissolved particles, such as salts and glucose, in the serum) and therefore in maintaining the volume of water in the extracellular fluid (the fluid space that surrounds cells). This is necessary to protect cells from sudden increases or decreases in water content, which are capable of interfering with proper cell function. Normal serum osmolality ranges from about 285 to 300 milliosmoles per kilogram (mOsm/kg) in healthy people. Vasopressin and a hormone called oxytocin evolved from a single primordial neurohypophyseal hormone called vasotocin, which is present in lower vertebrates.

Special nerve cells called osmoreceptors in the hypothalamus are very sensitive to changes in serum osmolality. The osmoreceptors are closely associated with the same nerve cells that produce and secrete vasopressin. Serum osmolality that increases or decreases by as little as 1 percent can cause respective decreases or increases in vasopressin release. The immediate effect of an increase in serum osmolality—for example, if a person becomes dehydrated (e.g., loses water by excessive perspiration)—is a stimulation the osmoreceptors. This stimulation leads to the separation of vasopressin from molecules of neurophysin, to which vasopressin is loosely attached within the secretory cells. Vasopressin is then released from the posterior pituitary gland, leading to the subsequent retention of water by the kidneys. Conversely, the immediate effect of a decrease in serum osmolality—for example, if a person becomes overhydrated (e.g., drinks too much water)—is the inhibition of the osmoreceptors. This inhibition leads to a decrease in vasopressin secretion and a subsequent increase in water excretion. The osmoreceptors are also closely linked to the thirst centre, which is stimulated by high serum osmolality and is inhibited by low serum osmolality in the same way as is vasopressin secretion.

In the kidneys, vasopressin acts on the cells of the collecting ducts. These cells contain receptors for vasopressin that are linked to vesicles that contain special water channels (aquaporins). When the cells are stimulated by vasopressin, the aquaporins fuse with the region of the cell membrane that is exposed to urine, allowing water to enter the cells. The water is then returned to the circulation. This causes the volume of urine to decrease and the urinary content of sodium, chloride, and other substances to increase. When this occurs, the urine is said to be concentrated.

Diagram of a human figure showing the full nervous system, including the brain, spinal cord, and branching peripheral nerves throughout the body, with labels for each part.

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