Which anti-hypertensive agent acts directly on blood vessels rather than the central nervous system?

The correct answer is Hydralazine, as it is an anti-hypertensive agent that works by directly relaxing the smooth muscles of blood vessels, leading to vasodilation. This mechanism of action reduces peripheral vascular resistance and ultimately lowers blood pressure.

Clonidine, while also an anti-hypertensive, primarily exerts its effects through central nervous system action by stimulating alpha-2 adrenergic receptors in the brain, which decreases sympathetic outflow and reduces blood pressure. Carvedilol and Metoprolol are both beta-blockers that mainly affect heart rate and cardiac output; their primary mechanism is through beta-adrenergic receptor blockade.

In summary, Hydralazine’s direct action on blood vessels distinguishes it from the other options, which primarily influence blood pressure through central nervous system pathways or by affecting the heart directly.