Glibenclamide (glyburide) is a sulfonylurea oral hypoglycemic. The initial molecular event by which sulfonylureas stimulate insulin secretion from pancreatic beta cells is:

• A Opening of voltage-gated calcium channels directly
• B Inhibition of hepatic gluconeogenesis via AMPK
• C Activation of GLP-1 receptors on beta cells
• D Closure of ATP-sensitive potassium (K-ATP) channels ✓

Explanation

Sulfonylureas bind to the SUR1 subunit of K-ATP channels on pancreatic beta cells, causing channel closure. This depolarizes the cell, opens voltage-gated calcium channels, and triggers insulin exocytosis. Option A is a downstream consequence, not the initial event. Option C describes incretin action. Option B describes metformin's mechanism.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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