Adrenalin

The adrenalin is at the same time a Hormone and a Neurotransmetteur pertaining to the family of the Catécholamine S. This molecule bears also the name of épinéphrine , of the Greek ear and nephros meaning on the kidney . Adrenalin is secreted in answer in a state of Stress or for an physical-activity, involving an acceleration of the cardiac rhythm, an increase in the force of the contractions of the Cœur and a rise of the blood Pressure. She meets an energy requirement, for example to face the danger.

Pharmacology

Adrenalin is sécrétee by the glands suprarenals. Adrenalin takes effect by setting on the receiving adrenergic of the target cells.

The effects of adrenalin strongly depend on the amount and the distribution on the receivers alpha and beta on the bodies. Globablement, the receivers alpha are in greater number than the receivers beta, but the latter have stronger Affinité for adrenalin.

Thus, at low dose (0,1 µg/kg/min), adrenalin is preferentially fixed on the receivers beta. The stimulation of the receivers beta-1 involves an increase in the force and frequency of contraction of the Cœur (effect Inotrope and positive Chronotrope), an activation of the Lipolyse in fat fabric. The fixing of adrenalin on the receivers beta-2 causes a Vasodilatation, a Hypotension, a Hypoglycémie, a bronchodilatation, and a relieving of the muscles of the Intestin, Vessie and Utérus.

With stronger amount, adrenalin stimulates at the same time the receivers alpha and beta. However, the heart put aside, the receivers alpha are majority on the bodies and their effects prevail: there is mainly an increase in the Glycolyse in the Foie, a Vasoconstriction (dominating the vasodilatation due to the receivers beta-2), a arterial hypertension. The heart has only receivers béta-1 and answers, whatever the amount of adrenalin, by a rise of the force and frequency of the contractions.

On the level of the lipidic metabolism, adrenalin has an action identical to that of the Glucagon, it supports the hydrolysis of the Glycéride S while releasing from the Glycérol and the fatty-acids.

To consult the article Regulation of the glycemia for the role of adrenalin in this phenomenon.

Metabolism

Adrenalin is mainly secreted in the Sang by the cells chromaffines of the adrenal medulla, in answer to a direct stimulation by the Neuron S of the sympathetic nervous system. The synthesis of adrenalin is carried out starting from an other catecholamine, the Noradrénaline, by methylation thanks to a Enzyme, the phényléthanolamine N-méthyltransférase ( to also see the metabolism of catecholamines .)

Adrenalin lasts short action (about 2 minutes) because it is quickly degraded by two enzymes, the catéchol-oxyméthyltransférase (COMT) and the Monoamine oxydase (MAO).

Medical use

The adrenalin in injection is the drug of choice for the treatment of the cardio-circulatory stops, primarily in the event of asystolie (failure of the cardiac muscle without turbid of the rate/rhythm). It is also used in the anaphylactic shocks (of allergic origin), and in reanimation, at the time of some states of shock serious. Its handling remains delicate, because an overdose can involve Tachycardie and Troubles cardiac rhythm which can worsen the state of the patient.

Adrenalin is sometimes injected with low dose into intra-articular during examinations arthrographic S in partnership with a Produit of contrast, its action allows a deceleration of the elimination of the product of contrast (in particular its absorption by the Cartilage S and the Synoviale) and thus to lengthen the duration of the examination.

Synthesis of adrenalin starting from phenylalanine

  1. the Phénylalanine is hydroxylated, which gives…

  2. Tyrosin is hydroxylated, which gives…
  3. the DOPED is décarboxylé, which gives…
  4. the Dopamine is hydroxylated, which gives…
  5. the Noradrénaline is methylated, which gives…
  6. the adrenalin

Related articles

Simple: Epinephrine

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