Alpha-2 adrenergic receptor

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The α2 receptor is a type of adrenergic receptor.

Effect

The α2 receptor has several, general, functions in common with other α-receptors, but also has individual effects.

General

Common (or still unspecified) effects include:

Individual

Individual actions of the α2 receptor include:

Mechanism

A G protein - Gi renders adenylate cyclase inactivated, resulting in decrease of cAMP.

The relaxation of gastrointestinal tract motility is by presynaptic inhibition[4], where transmitters inhibit further release by homotropic effects.

Agonists

adrenaline has higher affinity for the alpha-2 receptor than has noradrenaline, which, in turn, has much higher affinity than has isoprenaline.[4] Other agonists include:

* denotes selective agonists to the receptor.

Antagonists

(Alpha blockers)

* denotes selective agonists to the receptor.

Types

There are three types of α2 receptors: ADRA2A, ADRA2B, ADRA2C.

See also

References

  1. Woodman OL, Vatner SF (1987). "Coronary vasoconstriction mediated by α1- and α2-adrenoceptors in conscious dogs". Am. J. Physiol. 253 (2 Pt 2): H388–93. PMID 2887122.
  2. Elliott J (1997). "Alpha-adrenoceptors in equine digital veins: evidence for the presence of both α1 and α2-receptors mediating vasoconstriction". J. Vet. Pharmacol. Ther. 20 (4): 308–17. doi:10.1046/j.1365-2885.1997.00078.x. PMID 9280371.
  3. Sagrada A, Fargeas MJ, Bueno L (1987). "Involvement of α1 and α2 adrenoceptors in the postlaparotomy intestinal motor disturbances in the rat". Gut. 28 (8): 955–9. doi:10.1136/gut.28.8.955. PMID 2889649.
  4. 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Rang, H. P. (2003). Pharmacology. Edinburgh: Churchill Livingstone. ISBN 0-443-07145-4. Page 163
  5. Wright EE, Simpson ER (1981). "Inhibition of the lipolytic action of beta-adrenergic agonists in human adipocytes by alpha-adrenergic agonists". J. Lipid Res. 22 (8): 1265–70. PMID 6119348.
  6. 6.0 6.1 Fitzpatrick, David; Purves, Dale; Augustine, George (2004). "Table 20:2". Neuroscience (Third Edition ed.). Sunderland, Mass: Sinauer. ISBN 0-87893-725-0.
  7. Khan ZP, Ferguson CN, Jones RM (1999). "alpha-2 and imidazoline receptor agonists. Their pharmacology and therapeutic role". Anaesthesia. 54 (2): 146–65. doi:10.1046/j.1365-2044.1999.00659.x. PMID 10215710.
  8. online-medical-dictionary.org

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