FIG. 3.

H₂O₂ measurements from single MCs after stimulation with the phorbol ester TPA. CA experiments were conducted at 650 mV in PBS-I buffer. A 10 μm Pt-UME (vs. Ag/AgCl) was placed 5–8 μm above different individual MCs in the experiments shown in (A) and (D). (A) CA measurement of a single MC after stimulation with TPA (red trace). The solvent DMSO (0.2%) was used in a control experiment with the same cell, but preceding TPA stimulation (black trace). (B) Average total current increase (±SEM) of single cells as shown in (A) after application of DMSO (161 ± 33.6 fA; n = 25) or TPA stimulation (639.8 ± 108.8 fA; n = 23). (C) Bright-field image of an MC and the tip of the UME. (D) Three consecutive 2D scans after TPA stimulation of the MC shown in (C) whose position is marked by dashed white circles. Numbers in the right upper corners refer to the time points indicated in (A) where another exemplary MC was measured. 2D scan images (D) are representative for n = 17 different scanning experiments with individual cells. Settings: constant height; scanning rate x = 2 μm/s, 50-nm resolution; y = 2 μm, alternate mode; raw data, no compression. MC, monocyte; TPA, 12-O-tetradecanoylphorbol-13-acetate.