Figure 4.

Loop of Henle reabsorption during loop perfusion. (a) Early distal flow rate during loop of Henle microperfusion with standard late ATF (10 mM HCO₃; low bicarbonate). (b) Early distal flow rate during perfusion with 25 mM HCO₃ (high bicarbonate), demonstrating increased bicarbonate-dependent reabsorption in post-BNZ nephrons. (c) Electrical conductivity of the early distal nephron as a function of VLP in nephrons perfused with ATF. Conductivity is normalized to conductivity of standard late proximal ATF. The degree to which conductivity is reduced below ATF reflects the fraction of delivered solute reabsorbed from the water-impermeable ascending loop of Henle. Circles indicate controls; squares indicate post-BNZ nephrons.