Figure 1. Time course and Na+-dependence of L-carnitine uptake. The uptake of 12nM L-[3H]carnitine by HCLE (A) or HCjE (B) cells was measured at pH 7.4 and 37 °C in the presence or absence of Na+. For Na+-free buffer, NaCl was replaced by an equimolar concentration of choline. Values are the mean±SD (n=4).