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
All of the following peptides produce vasodilation in most vascular beds EXCEPT 
Select and explain. 
A. Endothelin, B. Bradykinin, C. Vasoactive intestinal peptide, D. Calcitonin gene-related peptide
A: Endothelin
Answer: A: Endothelin 
Explanation: Endothelin is a potent vasoconstrictor peptide produced by vascular endothelial cells. Other vasoconstrictor pep tides include angiotensin H, neuropeptide Y, and vasopressin. Bradykinin, vasoactive intestinal peptide, calcitonin gene-related peptide, and substance P cause vasodilation in most vascular beds. Other vasodilator peptides include atrial natriuretic peptide and neurotensin.