Histamine released from mast cell granules is a key mediator of the immediate transient increase in vascular permeability in acute inflammation. This effect is mediated through binding to which receptor on postcapillary venules?
- A H2 receptor
- B H3 receptor
- C H1 receptor ✓
- D H4 receptor
Correct answer: C. H1 receptor
Explanation
Histamine causes arteriolar vasodilation and contraction of endothelial cells in postcapillary venules, opening intercellular gaps, via the H1 receptor. H2 receptors mainly mediate gastric acid secretion and cardiac effects, while H3 and H4 receptors are largely neural and immunomodulatory respectively. Antihistamines used clinically for allergic reactions act at H1, which is the fact that distinguishes the correct answer from H2.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.