 Sodium (Na+), potassium (K+) and chloride (Cl−) ions are reabsorbed by active transport.The predominant mechanism of active transport in this segment is through the Na+/K+/Cl− co-transporter NKCC2 as well as the sodium/hydrogen exchanger NHE3.In total this segment accounts for approximately 25-30% of total Na+ reabsorption along the nephron.