Fig. 7.

Nicotine treatment suppresses poly(I:C)-induced intracellular Ca²⁺ increase in mouse RAW 264.7 macrophages. After nicotine treatment, RAW 264.7 macrophages were stimulated with TLR3 agonist poly(I:C) (20 μg/ml) or PBS. (A) typical fluorescence images of control and poly(I:C)-stimulated RAW264.7 cells captured at 4 minutes of recording in the presence or absence of nicotine. Scale bar represents 50 µm. (B) representative time courses of intracellular Ca²⁺ changes (fluo-4 fluorescence expressed as a ratio of individual cell fluorescence intensity [F] to its basal fluorescence intensity [F₀]) in response to stimulation with poly(I:C), poly(I:C) + nicotine, or nicotine alone from 8 cells per experiment. In the nicotine-only treatment group, nicotine (5 μg/ml) was added at the same time point with the poly(I:C) + nicotine group, and the fluorescence curve was recorded simultaneously to compare with the control group. (C) quantitative analysis of the inhibitory effect of nicotine on poly(I:C)-induced intracellular Ca²⁺ increase is captured at 4 minutes of stimulation. The fluorescence of nicotine-alone treatment group was also recorded at the same time point to compare with control group. Data are shown as mean ± S.E.M. from three independent experiments (*P < 0.001).