Table 2 H2 Receptor Antagonists
From: The Role of Antihistamines in the Treatment of Vasomotor Rhinitis
Receptor | H2 |
|---|---|
Signal conduction through | Gs |
Location of receptors | Widely expressed including: Mucosa of stomach, cardiac tissue, uterus, smooth muscle vascular bed, epithelium of mucosa of nose, submucosal glands in nose, central nervous system, immune cells |
Chromosome location | 5q35.3 |
Signal conduction induces | Increase in cyclic AMP, activation of adenyl cyclase |
Antagonists (reverse agonists) | Burimamide, cimetidine, dimaprit, famotidine, nizatidine, ranitidine, and others (it should be noted that a number of different H1 antagonists also show affinity for the H2 receptor |
Activities | Increased gastric acid secretion; increases vascular permeability producing a fall in blood pressure, flush, headache, and reflex tachycardia; stimulate mucus production in the lungs; direct chronotropic effect on atrium and inotropic action on ventricle; relaxation of esophageal sphincter; stimulation of suppressor T-cells; decrease in neutrophil and basophil chemotaxis and activation; proliferation of lymphocytes; activity of NK cells |
Nasal symptoms produced | Antagonism of the H2 receptor could potentially reduce the effect of histamine on nasal airway swelling, producing nasal decongestion |