Atrial natriuretic peptide lowers blood pressure partly by direct vascular action. Its vasodilator signal transduction differs from that of nitric oxide in which respect?

• A ANP activates soluble guanylate cyclase whereas NO activates particulate guanylate cyclase
• B ANP binds a membrane receptor with intrinsic guanylate cyclase activity, whereas NO activates soluble guanylate cyclase after diffusing into the cell ✓
• C Both act identically through the same receptor-linked guanylate cyclase
• D ANP signals through cAMP-dependent protein kinase, unlike NO which uses cGMP

Explanation

Natriuretic peptide receptor A is a single-pass membrane receptor whose intracellular domain is itself a guanylate cyclase; ligand binding generates cGMP directly, causing smooth muscle relaxation and natriuresis. Nitric oxide, being lipophilic, diffuses across the membrane and activates soluble guanylate cyclase in the cytosol. Both pathways converge on cGMP and reduced intracellular calcium, but the cyclase source distinguishes them. Option D is incorrect because ANP signaling is entirely cGMP dependent, never cAMP dependent.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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