Figure 2.

(a) Light microscopic side-view images of an intact substrate-attached A549 cell in PS (0), ILS (1), and after plasma permeabilization with digitonin (2). The corresponding perspective view of 3D cell models reconstructed by dual image surface reconstruction technique (as described in Methods) is shown on the right, from which absolute cell volume (in pl) was determined. (b) Permeabilization-induced relative cell volume changes. Initial absolute cell volume measured in PS (t = 0–5 min) was set to 1. When PS was changed to ILS, cells swelled to 1.35- ± 0.01-fold initial volume. After equilibration at t = 12 min, cells were permeabilized with 25 μg/ml digitonin (■) or 0.1% Triton X-100 (▾), which remained in the perfusate throughout the experiment. In another series of experiments, cells were permeabilized with 5 μg/ml digitonin for 2 min (□) or amphotericin B (7.5 μM, 8 min, ○). The detergent was washed away afterward with ILS. Representative traces are shown for n = 5 (amphotericin B) to n = 50 (digitonin). (c) Comparison of membrane permeabilization-induced swelling of three different cell lines A549 (■), 16HBE14o⁻ (○), and HL-60 (▴). Representative traces are shown for n = 50 (A549 cells) and n = 4 for two other cell lines. The thick horizontal bar indicates a 2 min period of digitonin application.