Amiloride applied to the tongue selectively abolishes the taste response to sodium chloride but leaves sucrose and quinine responses intact. This demonstrates that salt taste transduction depends on:

• A A G-protein coupled receptor activating phospholipase C
• B Blockade of voltage-gated calcium channels on the basolateral membrane
• C An epithelial sodium channel allowing direct Na influx into taste cells ✓
• D Proton entry through hydrogen ion channels depolarising the cell

Explanation

Salt taste in type I taste receptor cells is mediated by the amiloride-sensitive epithelial sodium channel ENaC: dietary sodium enters directly down its electrochemical gradient and depolarises the cell. Sweet, bitter, and umami use GPCRs coupled to gustducin, while sour taste uses proton-permeable channels, so options A and D describe other modalities. Amiloride blockade of ENaC specifically spares those pathways, exactly as observed.

Reference: Ganong Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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