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Epinephrine
(also adrenaline, epi in medical
jargon) is a hormone and acts as a neurotransmitter. Both
names mean the same: the Latin roots ad-+renes
and the Greek roots epi-+nephros
both literally mean "on/to the kidney" (referring
to the adrenal gland, which secretes
epinephrine).
Epinephrine
plays a central role in the stress reaction--the physiological
response to conditions that threaten the physical integrity of
the body. It is secreted by the adrenal medulla. When released
into the bloodstream, epinephrine acts to increase heart rate
and blood pressure, dilate
the pupils, elevate the blood sugar
level (by increased hydrolysis of glycogen to glucose), and redistribute
blood flow away from the skin and inner organs.
Epinephrine
is used as a drug in order to stimulate cardiac
action in cardiac arrest, as a vasoconstrictor in anaphylactic shock
and sepsis, and as a bronchodilator in acute
bronchial asthma. Allergy patients undergoing
immunotherapy can get an
epinephrine rinse before their allergan extract is administered.
Adverse reactions include palpitations, tachycardia, anxiety, headache,
tremor, hypertension, and acute pulmonary oedema.
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.
Chemically, epinephrine
is a catecholamine hormone, a
sympathomimetic monoamine derived from the amino acids phenylalanine and tyrosine. The chemical formula of epinephrine
is C9H13NO3. Its structure is
shown right.
Epinephrine was first
isolated and identified in 1897 by John Jacob Abel. Jokichi Takamine discovered
the same hormone in 1901, without knowing about the previous
discovery, and called it adrenaline. It was first artificially
synthesized in 1904 by Friedrich Stolz.
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