Figure 5.

PG/VG affects membrane fluidity and protein diffusion. (A) Confocal micrographs (x–z plane) of human bronchial epithelial cultures (HBECs) stained with calcein (green) and Pixie Dust e-liquid excited at 405 nm (red). Representative images of three independent experiments were taken before and 10 minutes after addition of e-liquid. The dashed yellow lines indicate the apical surface of the culture. (B) Representative x–y-plane confocal micrograph of HEK293T cells (gray differential interference contrast image) before and after 5 minutes of exposure to Pixie Dust e-liquid (purple). (C) Emission scan of merocyanine 540 (M540) in HBECs. Black circles, vehicle at 37°C; red squares, 3% PG/VG at 37°C; blue triangles, vehicle at 4°C. All n = 9 cultures from three separate donors. (D and E) Fluorescence recovery after photobleaching of (D) Orai1-YFP and (E) Ano1-GFP in HEK293T cells after vehicle or 3% PG/VG exposure. Cells transfected with Orai1-YFP or Ano1-GFP were exposed to PG/VG for 1 hour before FRAP was measured. Data shown as means ± SEM. All n = 12–16 cultures per group from three or four independent experiments. *P ≤  0.05. Ano1 = anoctamin 1; FRAP = fluorescence recovery after photobleaching; GFP = green fluorescent protein; Orai1 = calcium release-activated calcium modulator 1; PG/VG = propylene glycol/vegetable glycerin; RG = Ringer’s glucose; YFP = yellow fluorescent protein.