A naturally occurring catecholamine hormone that functions as a neurotransmitter in the sympathetic nervous system. Norepinephrine directly stimulates adrenergic receptors. Stimulation of alpha-adrenergic receptors causes vasoconstriction of the radial smooth muscle of the iris, arteries, arterioles, veins, urinary bladder, and the sphincter of the gastrointestinal tract. Stimulation of beta-1 adrenergic receptors causes an increase in myocardial contractility, heart rate, automaticity, and atrioventricular (AV) conduction while stimulation of beta-2 adrenergic receptors causes bronchiolar and vascular smooth muscle dilatation.
Definition (NCI)
A synthetic phenylethylamine that mimics the sympathomimetic actions of the endogenous norepinephrine. Norepinephrine acts directly on the alpha- and beta-adrenergic receptors. Clinically, norepinephrine is used as a peripheral vasoconstrictor that causes constriction of arterial and venous beds via its alpha-adrenergic action. It is also used as a potent inotropic and chronotropic stimulator of the heart mediated through its beta-1 adrenergic action.
Definition (NCI)
A chemical made by some nerve cells and in the adrenal gland. It can act as both a neurotransmitter (a chemical messenger used by nerve cells) and a hormone (a chemical that travels in the blood and controls the actions of other cells or organs). Noradrenaline is released from the adrenal gland in response to stress and low blood pressure.
Definition (MSH)
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.
Definition (CSP)
precursor of epinephrine; widespread central and autonomic neurotransmitter, principal transmitter of most postganglionic sympathetic fibers; secreted by the adrenal medulla; used pharmacologically as a sympathomimetic.
Concepts
Organic Chemical (T109)
, Pharmacologic Substance (T121)
, Neuroreactive Substance or Biogenic Amine (T124)