Histamine H2 receptor

H2 receptors positively coupled to adenylate cyclase via Gs. It is a potent stimulant of cAMP production. It increases the intracellular Ca2+ concentrations and release Ca2+ from intracellular stores.

The drug Betazole is an example of a Histamine H2 receptor agonist.

Location

 * Gastric parietal cells (oxyntic cells)
 * Vascular smooth muscle
 * Neutrophils
 * Central nervous system
 * Heart
 * Uterus

Response

 * Stimulation of gastric acid secretion
 * Smooth muscle relaxation
 * Vasodilation
 * Inhibit antibody synthesis, T-cell proliferation and cytokine production

Vasodilation
In vasodilation, PKA activity causes phosphorylation of MLCK, decreasing its activity, resulting in dephosphorylation of MLC of myosin. The smooth muscle relaxation leads to vasodilation.

H2-receptor agonists and antagonists
see H2-receptor agonist and H2-receptor antagonist