Most Potent Vasoconstrictor in the Body

The most potent vasoconstrictor produced in the body is:

Correct Answer: Endothelin

Endothelin is the most potent vasoconstrictor produced in the body. It is secreted by vascular endothelial cells and causes sustained, powerful vasoconstriction.

Classification of Vasoconstrictors

• Endothelin — Most potent vasoconstrictor
• Vasopressin (ADH) — antidiuretic hormone; also causes vasoconstriction
• Angiotensin II — important in renin-angiotensin-aldosterone system (RAAS)
• Norepinephrine — sympathetic neurotransmitter; acts on α-receptors
• Dopamine — at high doses causes vasoconstriction
• Thromboxane A₂ — also causes platelet aggregation
• Neuropeptide Y (NPY)

Classification of Vasodilators (for contrast)

• Nitric oxide (NO) — Most potent vasodilator
• Atrial natriuretic peptide (ANP)
• Histamine, Heparin, Bradykinin
• Prostacyclin (PGI₂), PGE₂
• VIP (vasoactive intestinal peptide)

Special Case: Epinephrine

Epinephrine acts as BOTH vasoconstrictor AND vasodilator depending on receptor: α-receptor → vasoconstriction; β-receptor → vasodilation. Its affinity for β-receptors is greater than for α-receptors.