The H2 subclass of histamine receptor mediates gastric acid secretion. It can be found in the parietal cells located in the stomach lining. Also appears to regulate gastrointestinal motility and intestinal secretion. Excess gastric juice production may result in gastroenteritis. It has a possible role in the regulation of cell growth and differentiation.

 

The activity of this receptor is mediated by GPCR which activates adenylyl cyclase and, through a separate GPCR-dependent mechanism, the protein kinase C (PKC) signalling pathway. H2-Rs are positively coupled to adenylyl cyclase via a Gs protein and mediate most of their effects by altering the intracellular levels of cAMP (Kubota et al., 2011).

 

H2-R antagonists are widely used to treat peptic ulcer. Common antagonists on the market are ranitidine, cimetidine and tiotidine. Dimaprit is fairly selective H2 agonist due to discrimination towards H1 and H3 receptors.