Which condition activates gustatory receptors for salty taste?

Which condition activates gustatory receptors for salty taste?

• A. Increased K+ concentration outside gustatory cells
• B. Increased Na+ concentration inside gustatory cells
• C. Increased Cl- concentration outside gustatory cells
• D. Increased Na+ concentration outside gustatory cells

Answer: (D)

Salty taste relies on Na+ entering the taste receptor cells. The sodium ions in the extracellular fluid move into the cell through sodium-permeable channels, driven by the concentration gradient. This inward Na+ current depolarizes the cell, opening voltage-gated calcium channels and triggering neurotransmitter release to the gustatory nerve fibers, signaling the salty sensation. Therefore, increasing Na+ outside the gustatory cells provides the driving force for Na+ entry and initiates the transduction cascade. Increasing Na+ inside would not produce the necessary inward current, and changes in outside K+ or Cl- don’t generate the specific Na+-driven depolarization that underlies salty taste.

Salty taste relies on Na+ entering the taste receptor cells. The sodium ions in the extracellular fluid move into the cell through sodium-permeable channels, driven by the concentration gradient. This inward Na+ current depolarizes the cell, opening voltage-gated calcium channels and triggering neurotransmitter release to the gustatory nerve fibers, signaling the salty sensation. Therefore, increasing Na+ outside the gustatory cells provides the driving force for Na+ entry and initiates the transduction cascade. Increasing Na+ inside would not produce the necessary inward current, and changes in outside K+ or Cl- don’t generate the specific Na+-driven depolarization that underlies salty taste.