In intestinal epithelial cells, glucose moves from lumen into the cell against its concentration gradient via SGLT1, a Na⁺/glucose symporter. Which condition would most reduce glucose uptake by SGLT1 within seconds?
- Acheck_circle
Inhibition of the basolateral Na⁺/K⁺-ATPase
- B
An increase in luminal glucose concentration
- C
Activation of apical aquaporins
- D
Increased cytoplasmic K⁺
Explanation
SGLT1 uses the inward Na⁺ gradient (maintained by the basolateral Na⁺/K⁺-ATPase) as its energy source. Block the pump → Na⁺ gradient collapses → secondary active glucose uptake fails.