adrenergic blocking agent


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Related to adrenergic blocking agent: antiarrhythmic

ad·re·ner·gic block·ing a·gent

a compound that selectively blocks or inhibits responses to sympathetic adrenergic nerve activity (sympatholytic agent) and to epinephrine, norepinephrine, and other adrenergic amines (adrenolytic agent); two distinct classes exist, α- and β-adrenergic receptor blocking agents.

adrenergic blocking agent

ad·re·ner·gic block·ing a·gent

(ad'rĕ-nĕr'jik blok'ing ā'jĕnt)
A compound that selectively blocks or inhibits responses to sympathetic adrenergic nerve activity (sympatholytic agent) and to epinephrine, norepinephrine, and other adrenergic amines (adrenolytic agent); two distinct classes exist, alpha- and beta-adrenergic receptor blocking agents.

ad·re·ner·gic block·ing a·gent

(ad'rĕ-nĕr'jik blok'ing ā'jĕnt)
Compound that selectively blocks or inhibits responses to sympathetic adrenergic nerve activity (sympatholytic agent) and to epinephrine, norepinephrine, and other adrenergic amines (adrenolytic agent); two distinct classes exist, α- and β-adrenergic receptor blocking agents.

adrenergic

1. activated by, characteristic of, or secreting epinephrine or substances with activities similar to those of epinephrine. The term is applied to those nerve fibers of the sympathetic nervous system that release norepinephrine (and possibly small amounts of epinephrine) at a synapse when a nerve impulse passes.
2. an agent that acts like epinephrine. Called also sympathomimetic.

adrenergic agents
sympathomimetic amines which exert their effects on adrenergic receptors of effector cells innervated by the sympathetic nervous system. The administration of these adrenergic agonists mimics the physiological effects of sympathoadrenal discharge.
adrenergic alpha-blockers, beta-blockers
see adrenergic blockade.
adrenergic amines
these are the sympathomimetic amines. They have similar but not identical structures and actions. Epinephrine, norepinephrine and isoproterenol are catecholamines but differ in their effects. Norepinephrine is primarily an activator of alpha-receptors whereas isoproterenol is a selective beta-receptor agonist. Epinephrine is an active agonist for both alpha- and beta-receptors. Ephedrine is the classical noncatecholamine sympathetic agonist.
adrenergic blockade
adrenergic blocking agents prevent the activation of adrenergic receptors. They may be alpha-blockers, e.g. ergot, or beta-blockers such as propranolol.
adrenergic blocking agent
a drug that blocks the secretion of epinephrine and norepinephrine at the postganglionic nerve endings of the sympathetic nervous system. By blocking these adrenergic substances, which cause constriction of blood vessels and increased cardiac output, adrenergic blocking agents produce a dilatation of the blood vessels and a decrease in cardiac output.
adrenergic nerves
see adrenergic (1) (above).
adrenergic nervous system
see sympathetic nervous system.
adrenergic receptors
class of receptors named after the action of adrenalin(e), the alternative name for epinephrine. Alpha receptors, which are stimulated by norepinephrine and blocked by agents such as phenoxybenzamine, are categorized into two classes, α1 and α2, which have different actions. α1 adrenergic actions include contraction of the iris, decreased motility in the intestine, and potassium and water secretions from the salivary glands. α2 adrenergic receptors inhibit adenylate cyclase, rather than activating it. Beta receptors, which are stimulated by epinephrine and blocked by agents such as propranolol, are also categorized into two types; β1 adrenergic receptors, which produce lipolysis and cardiostimulation, and β2 adrenergic receptors, which produce bronchodilatation and vasodilatation.