Figure 1.

Glucose reabsorption in the renal proximal tubule. The basolateral Na⁺/K⁺ ATPase pumps Na⁺ out and K⁺ into the cell to establish an inward Na⁺ gradient. This gradient is used for Na⁺ and glucose co-transport across the luminal brush border of the early proximal tubule through SGLT2, and the glucose is passively returned via GLUT2 to the interstitium/bloodstream. In the late proximal tubule, SGLT1 is responsible for ‘mopping up’ remaining luminal glucose, while the role of basolateral GLUT1-facilitated glucose transport in this segment remains unclear. Apical efflux of K⁺ maintains the electrogenic gradient.

Na⁺/K⁺ ATPase: sodium potassium adenosine triphosphatase active transporter; SGLT: sodium-dependent glucose transporter; GLUT: facilitative glucose transporter.