Electronic cigarettes cause alteration in cardiac structure and function in diet-induced obese mice

Fig 1. Body weight and plasma nicotine, cotinine, and FAA levels. (A) Body weight measured over 12 weeks in mice exposed to saline and e-cigarettes in the absence or presence of nicotine. Nicotine delivered through e-cigarettes (2.4% nicotine) significantly reduces body weight in mice on an HFD compared to HFD-fed mice exposed to saline or e-cigarette (0% nicotine) aerosol. There is no difference in body weight between mice on an HFD exposed to saline or e-cigarette (0% nicotine) aerosol. (B) Plasma nicotine and cotinine levels in mice exposed to e-cigarette. (C) Plasma FAA levels in e-cigarette and saline-exposed mice. Values are given as means ± SE of 5 mice per group. * P<0.05; ** P<0.01.

Fig 2. E-cigarette (2.4% nicotine) plus HFD induces left ventricular ultrastructural abnormalities in obese mice. (A-D) Representative TEM images of left ventricular myofibrillar architecture in various treatment groups. CMs from saline-(A) or e-cigarette (0% nicotine)-exposed (B) mice on an HFD shows normal myofibrillar architecture and sarcomeric pattern with normal nuclei and abundant mitochondria (m). In contrast, CMs from e-cigarette (2.4% nicotine) plus HFD exposed mice shows varying degrees of abnormalities (C, D), indicative of cardiomyopathy, including ventricular intramyocardial lipid accumulation (yellow arrow) or ventricular steatosis (C, D), myofibrillar derangement, thinning, and destruction (asterisks), and mitochondrial hypertrophy (C, D). Scale bar = 1μm.

Fig 3. E-cigarettes (2.4% nicotine) trigger CM apoptosis. Compared to mice exposed to saline (A) or e-cigarette (0% nicotine) aerosol (B), where little or no apoptosis is detected, a significant increase in CM apoptosis (C) was detected in mice exposed to e-cigarettes (2.4% nicotine). Scale bar = 25 μm. (D) Quantitation of CM apoptosis. Values are given as means ± SE of 5 mice per group. * P<0.05. (E) Western blot analysis of active (cleaved) caspase 3.

Fig 4. E-cigarettes (2.4% nicotine) plus HFD inactivates AMPK. (A) Western blot analysis of ventricular expression of phospho(p)-AMPK, total AMPK, phospho (p)-ACC, total ACC shows that mice on an HFD exposed to e-cigarette have markedly decreased p-AMPK and p-ACC levels compared with mice on an HFD exposed to saline or e-cigarette (0% nicotine) aerosol. (B, C) Quantitation of band intensities. GAPDH in the immunoblot is shown as a loading control. P<0.05. Values are given as means ± SE of 5 mice per group. * P<0.05.

Fig 5. E-cigarettes (2.4% nicotine) plus HFD triggers oxidative stress. Immunohistochemical analysis of ventricular sections show increased expression of 4-HNE in mice exposed to e-cigarette (2.4% nicotine) compared with saline- or e-cigarette (0% nicotine)-treated mice (A). Western blot analysis shows increased 4-HNE levels in mice exposed to e-cigarette (B). (C) Quantitation of band intensities. Data for p-AMPK and p-ACC were normalized to GAPDH. P<0.05. Values are given as means ± SE of 5 mice per group. * P<0.05.