What percentage of sodium is reabsorbed in the proximal tubule?

The proximal tubule of the nephron plays a crucial role in the reabsorption of sodium. It is responsible for reabsorbing approximately 65-70% of the sodium filtered through the glomerulus. This process is essential for maintaining fluid and electrolyte balance in the body.

Sodium reabsorption in the proximal tubule occurs predominantly through active transport mechanisms. The Na+/H+ exchanger and sodium-glucose co-transporters are among the primary transporters facilitating this process. Additionally, the reabsorption of sodium in this segment is coupled with water, which occurs due to osmotic forces, thereby concentrating the remaining solutes in the tubular fluid.

Understanding the percentage of sodium reabsorbed in the proximal tubule is important for comprehending renal physiology and the overall function of the kidney in regulating sodium and fluid balance.