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Adrenaline

in Latin: glandula adrenalis - adrenal medulla
Synonym: Epinephrine

German: Adrenalin

1 Definition

Adrenaline|epinephrine is a hormone that refers to the group of catecholamine with the group-formula (OH)2C6H3–HCOH–CH2NH-CH3. It is an important neurotransmitter.

2 Metabolism

2.1 Synthesis

Epinephrine can be synthesized in the human organism from the amino acid, phenylalanine or tyrosine. The required reaction steps for the synthesis take mainly place in the chromaffin cells of the adrenal medulla. The postsynaptic neurons of the sympathetic don't have the enzyme N- methyl transferase, what leads to the fact that the synthesis of adrenaline from norepinephrine is not possible.

In the first step of adrenaline biosynthesis, the enzyme tyrosine hydroxylase provides the tyrosine molecule at C3-atom with a second hydroxylgroup and is thus than a 3.4-Dihydroxyphenylalanin (DOPA). After that the enzyme DOPA decarboxylase, decarboxylases the resulting molecule into biogenic amine dopamine.

With the hydroxylation of the side chain and with help of the dopamine hydroxylase, noradrenaline can be produced; at this step ascorbic acid is involved as a cofactor. In the last step, the N- methyl - transferase transfers a methyl group from S-adenosyl-methionine to the aminogroup of the side chain.

2.2 Destruction

Epinephrine can be enzymatically inactivated after the secretion into the bloodstream. This step is mediated by two enzymes:

3 Function

Epinephrine exerts its effects in the human organism at the so-called adrenoceptors. It increases the vascular tone, raises the blood pressure and the heart rate and acts catabolic to the glycogen metabolism and anabolic to the glycolysis. In addition, adrenaline ensures the reduction of triglyceride within the fat tissue.

4 Pathophysiology

You can find an overproduction of adrenaline at the so-called pheochromocytoma. At this process operate among others high blood pressure, sweating, headache and palpitations.

5 Pharmacology

Adrenaline is used at the Emergency and shocktherapy; especially for the acute raising of blood pressure and for the excitation of cardiac function during a cardiac arrest.

In addition, adrenaline is often mixed up with local anesthetic to minimize the hemorrhage at the surgical area by vasoconstriction and to avoid an absorption of the anesthetic into the blood.

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