Figure 4

Model-predicted sodium concentration and flow profiles in the nephron model. Simulations are conducted using the parameter values for the Dahl R rat (Table 1). A. &C. Sodium concentrations as functions of distance along the nephron are plotted for the descending and ascending limb, collecting duct, and interstitium. B. &D. Flows as functions of distance along the nephron are plotted for the descending and ascending limb and collecting duct. The upper panel (A & B) reports model predictions for the baseline case with q _d (0) = 0.300 ml·min⁻¹·g⁻¹ and P _a =125 mmHg. The lower panel (C &D) reports predictions for a lower pressure: q _d (0) = 0.252 ml·min⁻¹·g⁻¹ and P _a  = 95 mmHg. At the lower pressure the concentration gradient steepens and output flow drops to near zero.