Relations between [Na+]i (A), [K+]i (B), [Cl−]i (C), and Cl− influx by NKCC1. (A) The relation between [Na+]i and Cl− influx by NKCC1 for three different [Cl−]i (30, 80, and 130 mM) is shown. [K+]i is fixed at 130 mM. (B) The relation between [K+]i and Cl− influx by NKCC1 for three different [Cl−]i (30, 80, and 130 mM) is shown. [Na+]i is fixed at 5 mM. (C) The relation between [Cl−]i and Cl− influx by NKCC1 for three different [Na+]i (1, 5, and 15 mM) is shown. [K+]i is fixed at 130 mM. Extracellular [Na+], [K+], and [Cl−] are fixed at 140, 5, and 140 mM, respectively (A–C).