Adrenaline

adrenaline (ədrĕn`əlĭn, –lēn): see epinephrine.

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epinephrine

 or adrenaline

One of two hormones (the other being norepinephrine) secreted by the adrenal glands, as well as at some nerve endings (see neuron), where they serve as neurotransmitters. They are similar chemically and have similar actions on the body. They increase the rate and force of heart contractions, increasing blood output and raising blood pressure. Epinephrine also stimulates breakdown of glycogen to glucose in the liver, raising blood glucose levels, and both hormones increase the level of circulating free fatty acids. All these actions ready the body for action in times of stress or danger, times requiring increased alertness or exertion. Epinephrine is used in medical situations including cardiac arrest, asthma, and acute allergic reaction (see allergy). See also dopamine.

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adrenaline [ə′dren·əl·ən]

(biochemistry)

epinephrine

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Adrenaline 

(also epinephrine), a hormone of the medullary layer of the adrenal glands which plays an important part in the vital activity of animals and man. Adrenaline is a pyrocatechol derivative, l-methylaminoethanolpyro-catechol, with a molecular weight of 183.2. It is white, crystalline, and optically active. Soluble in hot water, acids, and bases, it is unstable and readily forms various transformation products. Adrenaline was isolated in 1901 and synthesized in 1905. It is formed from the amino acids phenylalanine and tyrosine in the chromaffinic (easily stained) granules of the adrenal glands, from where it is secreted into the bloodstream. The precursor of adrenaline in the organism is noradrenaline, a transmitter (mediator) of nerve impulses in the sympathetic nervous system.

Upon entering the blood, the adrenaline raises the oxygen consumption of organs and tissues and participates in the mobilization of glycogen, the cleavage of which leads to an increase of the sugar level in the blood (hyperglycemia). Adrenaline stimulates protein, carbohydrate, fat, and mineral metabolism; raises arterial blood pressure (primarily by constricting the small peripheral blood vessels); increases heart and respiration rates and the force of cardiac contractions; slows intestinal peristalsis; and so forth. Adrenaline content of the blood rises during emotional stress, increased muscular work, choking, chilling, and lowering of the sugar level in the blood (hypoglycemia). A number of diseases of the internal organs, the nervous system, the endocrine glands, and of other parts of the body are accompanied by an increase or decrease of the adrenaline content in the organism, which can complicate the course of the disease.

Adrenaline for therapeutic purposes is obtained from the adrenal glands of animals and also synthetically. An adrenaline hydrochloride solution is administered subcutaneously during drops in blood pressure and in cases of bronchial asthma and other allergic diseases, in local anesthesia, and for exsanguinating wounds during surgery. Sometimes it is used locally to stop bleeding. Adrenaline is contraindicated in cases of hypertension, atherosclerosis, and severe organic heart diseases.

REFERENCES

Adrenalin i noradrenalin. [Lectures of the conference held Dec. 1–3, 1962.] Moscow, 1964.
Matlina, E. Sh., and V. V. Men’shikov. Klinicheskaia biokhimiia katekholaminov. Moscow, 1967.

G. N. KASSIL’