Chronic Adaptations of Na+/H+ Exchange in Renal Disease

The renal proximal tubule absorbs the bulk of the filtered load of sodium and water and, as such, is the principal energy-consuming component of the kidney. The principal transport process which translocates filtered sodium from the lumen of the proximal tubule to the cell interior is Na⁺/H⁺ exchange ¹ . When renal mass is reduced, or when disease alters glomerular function, tubular absorption of fluid adapts so that a relatively constant fraction of the filtered load is reclaimed ² . This chapter examines the basis for this remarkable “cross-talk” between glomerulus and tubule and highlights the role of Na⁺/H⁺ antiport activity in mediating both the transtubular transport adaptation and the process of renal growth in the diseased kidney.