Sulfonylureas lower blood glucose primarily by which molecular action on the pancreatic beta cell?

• A Activation of PPAR-gamma receptors on adipocytes
• B Closure of ATP-sensitive potassium channels, causing depolarization and calcium influx ✓
• C Inhibition of glucagon release from alpha cells
• D Competitive inhibition of intestinal alpha-glucosidase enzymes

Explanation

Sulfonylureas bind the SUR1 subunit of the beta-cell ATP-sensitive potassium channel, closing it. Depolarization opens voltage-gated calcium channels, calcium influx triggers exocytosis of preformed insulin. This action is independent of ambient glucose, which explains their hypoglycemia risk. Option A describes thiazolidinediones, option C is not their primary action, and option D describes acarbose.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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