Reserpine lowers blood pressure by depleting norepinephrine from sympathetic nerve endings. The molecular target of this depletion is:

• A VMAT2, the vesicular monoamine transporter that packages norepinephrine into storage vesicles ✓
• B Tyrosine hydroxylase, the rate-limiting enzyme of catecholamine synthesis
• C The norepinephrine transporter (NET) on the presynaptic membrane
• D Dopamine beta-hydroxylase within the storage vesicle

Explanation

Reserpine irreversibly blocks VMAT2, the transporter that pumps monoamines from cytosol into storage vesicles. Stored catecholamines leak into the axoplasm and are degraded by mitochondrial MAO, so transmitter stores fall and sympathetic transmission fails until new vesicles are made. Tyrosine hydroxylase inhibition is the mechanism of metyrosine, NET blockade defines cocaine and imipramine, and dopamine beta-hydroxylase is not the target.

Reference: Katzung's Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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