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[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Norepinephrine (noradrenaline)

Norepinephrine is the transmitter of sympathetic nerves and a hormone of the adrenal medulla. It raises blood pressure and alertness.

Updated 2026-11-01

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## Key facts

- Made from dopamine by dopamine β-hydroxylase inside storage vesicles.
- Released by postganglionic sympathetic neurons; it acts mostly on α₁, α₂ and β₁ receptors.
- PNMT methylates it to epinephrine in the adrenal medulla.
- Its main breakdown products are normetanephrine and VMA.

**Formula**
C₈H₁₁NO₃

**PubChem**
[CID 439260](https://pubchem.ncbi.nlm.nih.gov/compound/439260)

## Structure

- Dopamine with a hydroxyl on the β carbon of the side chain; a primary amine (epinephrine has an extra N-methyl).

## Clinical notes

- It is a first-line vasopressor in septic shock.
- Plasma normetanephrine is the most sensitive marker of norepinephrine-secreting phaeochromocytomas.
- Cocaine and tricyclic antidepressants block its reuptake.

## Pathways

- [Catecholamine synthesis and breakdown](https://durgical.com/en/biochemistry/pathways/catecholamine-synthesis-and-breakdown/)

## Related conditions

- [Phaeochromocytoma](https://durgical.com/en/conditions/phaeochromocytoma/)
- [Sepsis and septic shock](https://durgical.com/en/conditions/sepsis-and-septic-shock/)
- [Arterial hypertension](https://durgical.com/en/conditions/arterial-hypertension/)

## Related

- [Dopamine](https://durgical.com/en/biochemistry/molecules/dopamine/)
- [L-DOPA (levodopa)](https://durgical.com/en/biochemistry/molecules/l-dopa/)
- [Tyrosine hydroxylase](https://durgical.com/en/biochemistry/enzymes/tyrosine-hydroxylase/)
- [Vitamin C (ascorbic acid)](https://durgical.com/en/biochemistry/molecules/vitamin-c/)
- [S-adenosylmethionine (SAM)](https://durgical.com/en/biochemistry/molecules/s-adenosylmethionine/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme turns norepinephrine into epinephrine, and where?

PNMT, using SAM, mainly in the adrenal medulla.

## Which receptors does norepinephrine mainly act on?

α₁, α₂ and β₁; it has little effect on β₂ receptors.

## Which metabolite is measured for norepinephrine-secreting tumours?

Normetanephrine, made by COMT, in plasma or urine.

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Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Norepinephrine (CID 439260)](https://pubchem.ncbi.nlm.nih.gov/compound/439260) (PubChem, NCBI, 2026) · Public domain; [Dopamine beta-hydroxylase deficiency: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/dopamine-beta-hydroxylase-deficiency/) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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Representative model, for educational purposes only.

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