Which preformed mediator released by mast cell degranulation causes early vascular changes in acute inflammation by producing arteriolar dilation and opening intercellular gaps in postcapillary venules?

• A Histamine ✓
• B Leukotriene C4
• C Prostaglandin D2
• D Platelet activating factor

Explanation

Histamine is stored preformed in mast cell granules and acts within minutes through H1 receptors to dilate arterioles and increase venular endothelial permeability by causing transient contraction of endothelial cells, creating intercellular gaps. Leukotriene C4 and prostaglandin D2 are synthesized de novo from arachidonic acid after stimulation rather than stored preformed, and their onset of action is slower than the immediate response described here.

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.