Epinephrine

:For the Deftones' album; see Adrenaline (album).

Actions in the body

Epinephrine plays a central role in the short-term stress reaction—the physiological response to threatening or exciting conditions (see Fight-or-flight response). It is secreted by the adrenal medulla. When released into the bloodstream, epinephrine binds to multiple receptors and has numerous effects throughout the body. It increases heart rate and stroke volume, dilates the pupils, and constricts arterioles in the skin and gut while dilating arterioles in leg muscle. It elevates the blood sugar level by increasing hydrolysis of glycogen to glucose in the liver, and at the same time begins the breakdown of lipids in fat cells.

Related Topics:
Stress - Fight-or-flight response - Adrenal medulla - Receptors - Heart rate - Stroke volume - Pupil - Arterioles - Hydrolysis - Glycogen - Glucose - Lipids

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Epinephrine is used as a drug to promote peripheral vascular resistance via alpha-stimulated vasoconstriction in cardiac arrest and other cardiac disrhythmias resulting in diminished or absent cardiac output, such that blood is shunted to the body's core. This beneficial action comes with a significant negative consequence, increased cardiac irritability, which may lead to additional complications immediately following an otherwise successful resuscitation. Alternatives to this treatment include vasopressin, a powerful antidiuretic which also promotes peripheral vascular resistance leading to blood shunting via vasoconstriction, but without the attendant increase to myocardial irritability.

Related Topics:
Drug - Vasoconstriction - Cardiac arrest - Vasopressin

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Epinephrine is also used as a vasoconstrictor in anaphylaxis and sepsis, and as a bronchodilator for asthma if specific beta-2-adrenergic agonists are unavailable or ineffective. Allergy patients undergoing immunotherapy can get an epinephrine rinse before their allergen extract is administered. Adverse reactions to epinephrine include palpitations, tachycardia, anxiety, headache, tremor, hypertension, and acute pulmonary edema.

Related Topics:
Vasoconstrictor - Anaphylaxis - Sepsis - Bronchodilator - Asthma - Beta-2-adrenergic agonist - Immunotherapy - Tachycardia - Hypertension - Pulmonary edema

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

A pheochromocytoma is a tumor of the adrenal gland (or, rarely, the ganglia of the sympathetic nervous system) which secretes excessive amounts of catecholamines, usually epinephrine.

Related Topics:
Pheochromocytoma - Catecholamine

~ ~ ~ ~ ~ ~ ~ ~ ~ ~