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Related to alpha receptor: beta receptor
any of the postulated adrenergic components of receptor tissues that respond to norepinephrine and to various blocking agents. The activation of alpha receptors causes physiologic responses such as increased peripheral vascular resistance, pupil dilation, and contraction of arrector muscles. Also called alpha-adrenergic receptor. Compare beta receptor.
alpha receptorA pair of G protein-coupled cell membrane receptors in the sympathetic nervous system, which evoke an excitatory response of smooth muscle cells to catecholamines.
Alpha1 (Gq) coupled receptors cause smooth muscle contraction, resulting in vasoconstriction in the skin, GI tract, kidney and brain, as well as causing smooth muscle contraction in the ureter, vas deferens, arrector pili (hair–“goosebumps”), pregnant uterus, and elsewhere. Alpha1 receptor activation is also linked to glycogenolysis and gluconeogenesis in fat and liver, sweating, and sodium absorption in the kidneys.
Alpha2 (Gi) coupled receptors inhibit insulin secretion, trigger glucagon release (pancreas), contract GI sphincters, inhibit presynaptic release of noradrenaline in the CNS, and increase platelet aggregation.