Question:
Which of the following drugs produces vascular smooth muscle relaxation primarily by opening potassium channels, leading to membrane hyperpolarization?
Which of the following drugs produces vascular smooth muscle relaxation primarily by opening potassium channels, leading to membrane hyperpolarization?
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Vasodilators relax blood vessels through several different mechanisms. One important class works by opening ATP-sensitive potassium (K + ) channels in the vascular smooth muscle.
Updated On: Jun 24, 2026
- Fenoldopam
- Nitroprusside
- Minoxidil
- Verapamil
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The Correct Option is C
Solution and Explanation
Concept:
Vasodilators relax blood vessels through several different mechanisms. One important class works by opening ATP-sensitive potassium (K+) channels in the vascular smooth muscle.
How it works: When K+ channels open, potassium flows out of the cell, making the inside more negative (hyperpolarization). This hyperpolarized state keeps voltage-gated calcium channels closed, so less calcium enters, and the muscle relaxes. Minoxidil (via its active metabolite minoxidil sulfate) is the classic potassium-channel-opening vasodilator.
Why the other choices are wrong: Fenoldopam acts on dopamine D1 receptors. Nitroprusside releases nitric oxide to raise cGMP. Verapamil is a calcium-channel blocker. None of these acts mainly by opening K+ channels.
Answer: Option (3) — Minoxidil opens potassium channels causing hyperpolarization and vasodilation. (3)
Vasodilators relax blood vessels through several different mechanisms. One important class works by opening ATP-sensitive potassium (K+) channels in the vascular smooth muscle.
How it works: When K+ channels open, potassium flows out of the cell, making the inside more negative (hyperpolarization). This hyperpolarized state keeps voltage-gated calcium channels closed, so less calcium enters, and the muscle relaxes. Minoxidil (via its active metabolite minoxidil sulfate) is the classic potassium-channel-opening vasodilator.
Why the other choices are wrong: Fenoldopam acts on dopamine D1 receptors. Nitroprusside releases nitric oxide to raise cGMP. Verapamil is a calcium-channel blocker. None of these acts mainly by opening K+ channels.
Answer: Option (3) — Minoxidil opens potassium channels causing hyperpolarization and vasodilation. (3)
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