Net transepithelial reabsorption of Na+, Cl–, and water (JNa, JCl, and Jv, respectively) in isolated perfused S2 segments of proximal tubules from Cldn2+/+ and Cldn2−/− kidneys. Each datapoint is from one tubule of one mouse. Averaged data ± SEM of eight Cldn2+/+ and eight Cldn2−/− proximal tubules are shown at the left or right of each data set. *P < 0.001 vs. Cldn2+/+ tubules.