Reserpine lowers blood pressure by depleting catecholamine stores. Which molecular target accounts for this action?

• A Tyrosine hydroxylase
• B VMAT2, the vesicular monoamine transporter ✓
• C Dopamine beta-hydroxylase
• D The presynaptic alpha-2 autoreceptor

Explanation

Reserpine irreversibly blocks VMAT2, the transporter that packages norepinephrine and dopamine into synaptic vesicles. Vesicular storage fails, cytosolic monoamines are degraded by mitochondrial MAO, and transmitter stores fall over days to weeks, producing a long-lasting depletion that underlies both the antihypertensive effect and the depressive adverse effect. Tyrosine hydroxylase and dopamine beta-hydroxylase are synthetic enzymes that reserpine does not inhibit, and clonidine rather than reserpine is the prototypic alpha-2 agonist.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

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