H2 receptors are a type ofhistamine receptor found in many parts of the anatomy of humans and other animals. They are positively coupled toadenylate cyclase viaGs alpha subunit. It is a potent stimulant ofcAMP production, which leads to activation ofprotein kinase A.[5] PKA functions to phosphorylate certain proteins, affecting their activity. The drugbetazole is an example of a histamine H2 receptor agonist.
Histamine is a ubiquitous messenger molecule released frommast cells,enterochromaffin-like cells, andneurons.[5] Its various actions are mediated by histamine receptors H1, H2, H3 and H4. The histamine receptor H2 belongs to therhodopsin-like family ofG protein-coupled receptors. It is anintegral membrane protein and stimulates gastric acid secretion. It also regulates gastrointestinal motility and intestinal secretion and is thought to be involved in regulating cell growth and differentiation.[6] Histamine may play a role in penile erection.[7]
Vasodilation –PKA activity causes phosphorylation ofMLCK, decreasing its activity, resulting in MLC ofmyosin being dephosphorylated by MLCP and thus inhibiting contraction. The smooth muscle relaxation leads to vasodilation.[10]
Inhibition of neutrophil activation andchemotaxis[8]
^Cará AM, Lopes-Martins RA, Antunes E, Nahoum CR, De Nucci G (February 1995). "The role of histamine in human penile erection".British Journal of Urology.75 (2):220–224.doi:10.1111/j.1464-410x.1995.tb07315.x.PMID7850330.
^abcMaguire JJ, Davenport AP (29 November 2016)."H2 receptor".IUPHAR/BPS Guide to PHARMACOLOGY. International Union of Basic and Clinical Pharmacology. Retrieved20 March 2017.
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Traiffort E, Vizuete ML, Tardivel-Lacombe J, Souil E, Schwartz JC, Ruat M (Jun 1995). "The guinea pig histamine H2 receptor: gene cloning, tissue expression and chromosomal localization of its human counterpart".Biochemical and Biophysical Research Communications.211 (2):570–7.doi:10.1006/bbrc.1995.1851.PMID7794271.
Orange PR, Heath PR, Wright SR, Pearson RC (May 1996). "Allelic variations of the human histamine H2 receptor gene".NeuroReport.7 (7):1293–6.doi:10.1097/00001756-199605170-00015.PMID8817552.
Wang LD, Wang M, Todisco A, Grand E, del Valle J (Jun 2000). "The human histamine H(2) receptor regulates c-jun and c-fos in a differential manner".American Journal of Physiology. Cell Physiology.278 (6): C1246-55.doi:10.1152/ajpcell.2000.278.6.c1246.PMID10837353.
Brew OB, Sullivan MH (Sep 2001). "Localisation of mRNAs for diamine oxidase and histamine receptors H1 and H2, at the feto-maternal interface of human pregnancy".Inflammation Research.50 (9):449–52.doi:10.1007/PL00000269.PMID11603849.S2CID28710647.
Shayo C, Fernandez N, Legnazzi BL, Monczor F, Mladovan A, Baldi A, et al. (Nov 2001). "Histamine H2 receptor desensitization: involvement of a select array of G protein-coupled receptor kinases".Molecular Pharmacology.60 (5):1049–56.doi:10.1124/mol.60.5.1049.hdl:11336/31340.PMID11641433.S2CID24358588.
Esbenshade TA, Kang CH, Krueger KM, Miller TR, Witte DG, Roch JM, et al. (Feb 2003). "Differential activation of dual signaling responses by human H1 and H2 histamine receptors".Journal of Receptor and Signal Transduction Research.23 (1):17–31.doi:10.1081/RRS-120018758.PMID12680587.S2CID24392073.
