3.
Sodium dependence of taurine accumulation in hippocampal neuron cultures. Cells were exposed to tracer quantities of [3H]-taurine plus 1 μM unlabeled taurine in isoosmotic PBS containing the indicated sodium concentration for 20 min before sampling to determine cellular taurine accumulation. Sodium chloride was replaced with choline chloride in solutions with reduced sodium concentrations. Data points are the mean ± SEM of 4-5 independent measurements. The smooth line is drawn according to the best fit non-linear regression to a second order Michaelis-Menten equation as described in the text.