Nebivolol differs from other beta-1 selective blockers by additionally releasing nitric oxide via stimulation of which receptor pathway?
- A Beta-3 adrenoceptor → eNOS activation ✓
- B Alpha-2 adrenoceptor → cGMP pathway
- C D1 dopamine receptor → adenylyl cyclase
- D Imidazoline I1 receptor → PKC inhibition
Correct answer: A. Beta-3 adrenoceptor → eNOS activation
Explanation
Nebivolol at low doses is a highly selective beta-1 blocker, but it also stimulates beta-3 adrenoceptors on endothelial cells, which activates endothelial nitric oxide synthase (eNOS) via Gi-mediated pathway, releasing NO and causing vasodilation. This gives nebivolol a favourable haemodynamic profile with reduced peripheral resistance not seen with atenolol or metoprolol. Alpha-2 stimulation lowers sympathetic tone but does not produce NO via this mechanism; D1 and imidazoline receptors serve different vascular regulatory roles.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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