Histamine Receptor - Comparison

Comparison

Histamine receptors
Receptor Mechanism Function Antagonists
H1 Gq
  • ileum contraction
  • modulate circadian cycle
  • itching
  • systemic vasodilatation
  • bronchoconstriction (allergy-induced asthma)
  • H1-receptor antagonists
    • Diphenhydramine
    • Loratadine
    • Cetirizine
    • Fexofenadine
H2 Gs
↑ Ca2+
  • speed up sinus rhythm
  • Stimulation of gastric acid secretion
  • Smooth muscle relaxation
  • Inhibit antibody synthesis, T-cell proliferation and cytokine production
  • H2-receptor antagonists
    • Ranitidine
    • Cimetidine
    • Famotidine
    • Nizatidine
H3 Gi
  • Decrease Acetylcholine, Serotonin and Norepinephrine Neurotransmitter release in CNS
  • Presynaptic autoreceptors
  • H3-receptor antagonists
    • ABT-239
    • Ciproxifan
    • Clobenpropit
    • Thioperamide
H4 Gi
  • mediate mast cell chemotaxis.
  • H4-receptor antagonists
    • Thioperamide
    • JNJ 7777120

There are several splice variants of H3 present in various species. Though all of the receptors are 7-transmembrane g protein coupled receptors, H1 and H2 are quite different from H3 and H4 in their activities. H1 causes an increase in PIP2 hydrolysis, H2 stimulates gastric acid secretion, and H3 mediates feedback inhibition of histamine.

Read more about this topic:  Histamine Receptor

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