 With higher internal chloride concentrations, outward driving force for this ions increases, and thus channel opening leads to chloride leaving the cell, thereby depolarizing it.Put another way, increasing internal chloride concentration increases the reversal potential for chloride, given by the Nernst equation.Later in development expression of NKCC1 is reduced, while expression of a KCC2 K-Cl cotransporter increased, thus bringing internal chloride concentration in neurons down to adult values.