Effects of ascorbic acid on the uptake of serotonin in differentiated neuroblastoma cells

Ascorbic acid causes concentration-dependent and time-dependent effects on [3H]-serotonin (3H-5HT) uptake into differentiated neuroblastoma N-2a cells. Preincubation of cells with ascorbic acid inhibits both passive diffusion and active transport of 3H-5HT (0.1 microM). The kinetic characteristics of the active uptake process change with ascorbic acid treatment, resulting in an increase in the Km from 0.27 microM to 3.0 microM and in the Vmax from 453 to 2369 fmol/min/10(6) cells. This inhibitory effect of ascorbic acid appears to be due to its reducing properties.