Figure 3.

Nitric oxide (NO) bioavailability in the aorta. Aortic sections were studied from mice exposed to 16 and 60 wk of either air or electronic cigarette (e-cig) vape generated from e-cig liquid containing nicotine (NIC) 0 mg/mL (ECV-0), 6 mg/mL (ECV-6), or 24 mg/mL (ECV-24). A: sections were treated with the fluorescent nitric oxide (NO) probe diaminofluorescein-FM (DAF; green) and the nuclear fluorescent stain diamidino-2-phenylindole (DAPI; blue), with (air-exposed) or without the NO trap 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO treated), and visualized by confocal fluorescence microscopy. A 20-µm scale bar is shown toward the lower right corner of each figure. B and C: quantitation of the green fluorescence in A. ECV exposure decreased NO levels in the aorta in an exposure time- and a NIC-dependent manner. Data show the means ± SE of aortic sections from 4 mice. Analysis was done using two-way ANOVA followed by Bonferroni multiple-comparisons test. The differences were considered statistically significant at P ≤ 0.05. *Significant from air-exposed controls at P < 0.05; #significant from ECV-0 at P < 0.05; @significant from ECV-6 at P < 0.05; $significant from the same exposure at 16 wk at P < 0.05; †significant difference from ECV-24 in the absence of PTIO at P < 0.05.