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Histamine H2 receptor

Mammalian protein found in Homo sapiens

Summary

Mammalian protein found in Homo sapiens

H2 receptors are a type of histamine receptor found in many parts of the anatomy of humans and other animals. They are positively coupled to adenylate cyclase via Gs alpha subunit. It is a potent stimulant of cAMP production, which leads to activation of protein kinase A. PKA functions to phosphorylate certain proteins, affecting their activity. The drug betazole is an example of a histamine H2 receptor agonist.

Function

Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Histamine may play a role in penile erection.

Tissue distribution

Histamine H2 receptors are expressed in the following tissues: ;Peripheral tissues

  • Gastric parietal cells (oxyntic cells)
  • Vascular smooth muscle
  • Neutrophils
  • Mast cells
  • Heart
  • Genitourinary system (uterus, bladder)

;Central nervous system tissues

  • Caudate–putamen
  • Cerebral cortex (external layers)
  • Hippocampal formation
  • Dentate nucleus of the cerebellum

Physiological responses

Activation of the H2 receptor results in the following physiological responses:

  • Stimulation of gastric acid secretion (Target of anti-histaminergics (H2 receptors) for peptic ulcer disease and GERD)
  • Smooth muscle relaxation (Experimental histamine H2 receptor agonist used for asthma and COPD)
  • Inhibit antibody synthesis, T-cell proliferation and cytokine production
  • Vasodilation – PKA activity causes phosphorylation of MLCK, decreasing its activity, resulting in MLC of myosin being dephosphorylated by MLCP and thus inhibiting contraction. The smooth muscle relaxation leads to vasodilation.
  • Inhibition of neutrophil activation and chemotaxis

References

References

  1. "Entrez Gene: HRH2 histamine receptor H2".
  2. (February 1995). "The role of histamine in human penile erection". British Journal of Urology.
  3. (Sep 1997). "International Union of Pharmacology. XIII. Classification of histamine receptors". Pharmacological Reviews.
  4. (29 November 2016). "H2 receptor". International Union of Basic and Clinical Pharmacology.
  5. (1983). "Extragastric H2-receptors". Journal of Clinical Gastroenterology.
  6. Walter F., PhD. Boron. (2005). "Medical Physiology: A Cellular And Molecular Approach". Elsevier/Saunders.
Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

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