title: Physiological and pharmacological aspects of adrenergic receptor classification.
abstract: The questions raised are: what is the physiological or pharmacological basis for the differentiation into beta 1- and beta 2-, and alpha 1- and alpha 2-adrenergic receptors?; and do the neurotransmitter norepinephrine and the hormone epinephrine differ in their receptors? On the basis of a preference of beta 2- and alpha 2-adrenergic receptors for epinephrine, the hormone, and of beta 1-and alpha 1-receptors for norepinephrine, the neurotransmitter, it was postulated that the alpha 2- and beta 2-receptors are predominantly epinephrinergic in nature and located extrajunctionally and presynaptically whereas the alpha 1- and beta 1-receptors are predominantly norepinephrinergic in nature and located postsynaptically in the sympathetic terminal junction. The alpha 2- and beta 2-character of the presynaptic receptors matches that of the corresponding extrajunctional receptors. This indicates that a circulating catecholamine, namely epinephrine, is involved in the regulation of adrenergic transmitter release.
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000663:Amphibians; D000818:Animals; D002415:Cats; D002417:Cattle; D002965:Classification; D004837:Epinephrine / Q000502:physiology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D006801:Humans; D051379:Mice; D018377:Neurotransmitter Agents / Q000502:physiology; D009638:Norepinephrine / Q000502:physiology; D011817:Rabbits; D051381:Rats; D011941:Receptors, Adrenergic / Q000494:pharmacology / Q000502:physiology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000502:physiology
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D018377:Neurotransmitter Agents; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D009638:Norepinephrine; D004837:Epinephrine