Figure 4.

Effect of preincubation with 30 μM 5-HT on the [¹⁴C]guanidinium influx above basal influx in N1E-115 cells evoked by 2-min exposure to 30 μM 5-HT. Experiments were carried out using either sodium buffer (squares) or choline buffer (triangles). The responses are expressed as absolute values of [¹⁴C]guanidinium (pmol mg⁻¹protein) and were fitted to a monoexponential (choline) and biexponential (sodium) decay. (Inset) Normalization of values to the respective maximum signal (no preincubation with 5-HT) showing that a rate difference between both conditions developed within the first minute of 5-HT preincubation. Shown are means ±s.e.m. of n=3–6 experiments.