Naturally occurring hormone, acts as a peripheral vasoconstrictor

• A. Adrenaline
• B. Vasopressin
• C. Angiotensin II
• D. Endothelin

Answer: (B)

Vasopressin is a natural hormone that acts as a peripheral vasoconstrictor. It is produced in the hypothalamus and released from the posterior pituitary in response to low blood volume or high plasma osmolality. Its vasoconstrictive effect comes from acting on V1 receptors on vascular smooth muscle, raising systemic vascular resistance and blood pressure. It also has a water-retaining action via V2 receptors in the kidneys, but the vasoconstrictive role is the key reason it’s described as a peripheral vasopressor. While adrenaline can constrict some vessels and angiotensin II and endothelin are potent vasoconstrictors as well, vasopressin is the classic endogenous hormone specifically highlighted for its peripheral vasoconstrictive action.