This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Histamine causes all EXCEPT: 
Select and explain. 
A. Aeriolar dilatation, B. Increased permeability of venules, C. Constriction of large aeries, D. Platelet aggregation
D: Platelet aggregation
Answer: D: Platelet aggregation 
Explanation: Platelet aggregation REF: Robbin's pathology 7th edition page 63 Preformed histamine is present in mast cell granules and is released by mast cell degranulation in response to variety of stimuli. In humans histamine causes: Aeriolar dilatation Increased permeability of venules (however constricts large aeries) Via binding to H1 receptor on endothelial cells