Which is the neurotransmitter responsible for sympathetic vasoconstriction?

Correct option is C

Ans. (c)
Sol. Norepinephrine (also called noradrenaline) is the primary neurotransmitter released by sympathetic nerve endings. It acts on alpha-adrenergic receptors in blood vessels, causing vasoconstriction, which increases blood pressure. It plays a vital role in the 'fight or flight' response.
Explanation of each option:
· (a) Angiotensin – A hormone, not a neurotransmitter, that causes vasoconstriction and increases blood pressure.
· (b) Epinephrine – Also causes vasoconstriction, but it is more involved in hormonal responses via the adrenal medulla.
· (c) Norepinephrine – Correct answer. A sympathetic neurotransmitter responsible for vasoconstriction.
· (d) Serotonin – Mainly found in the brain and GI tract, involved in mood regulation, not sympathetic vasoconstriction.