Catecholamine

Catecholamines are chemical compoundsderived from the amino acidtyrosinethat act as hormonesor neurotransmitters. They are examples of phenethylamines.

Catecholamines are soluble (~50% loosely bound to plasma protein), and so they can circulate dissolved in blood.

The most abundant catecholamines are epinephrine(adrenaline), norepinephrine(noradrenaline) and dopamine. They are produced mainly from the adrenal medullaand the postganglionic fibersof the sympathetic nervous system. Adrenaline acts as a neurotransmitter in the central nervous systemand as a hormone in the blood circulation. Noradrenaline is primarily a neurotransmitter of the peripheral sympathetic nervous system but is also present in the blood (mostly through "spillover" from the synapsesof the sympathetic system).

High catecholamine levels in blood are associated with stress. Catecholamines cause general physiological changes that prepare the body for physical activity (fight-or-flight response). Some typical effects are increases in heart rate, blood pressure, and blood glucoselevels. Some drugs, like tolcapone(a central COMT-inhibitor), raise the levels of all the catecholamines.

Catecholamines have the distinct structure of a benzene ring with two hyroxyl groups and an amine group. They have a half-life of approximately a few minutes when cirulating in the blood and are formed from the amino acid, Tyrosine.

See also

• Catechol-O-methyl transferase
• Hormone
• Julius Axelrod
• Phenethylamines
• Steroid hormone
• Peptide hormone
• Sympathomimeticsde:Katecholamin

es:Catecolamina fr:Catécholamine is:Katekólamín fi:Katekoliamiini

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It uses material from the http://en.wikipedia.org/wiki/Catecholamine Wikipedia article Catecholamine.