E-cigarette use has surged, but the long-term health effects remain unknown. E-cigarette aerosols containing nicotine and acrolein, a combustion and e-cigarette byproduct, may impair cardiac electrophysiology through autonomic imbalance. Here we show in mouse electrocardiograms that acute inhalation of e-cigarette aerosols disturbs cardiac conduction, in part through parasympathetic modulation. We demonstrate that, similar to acrolein or combustible cigarette smoke, aerosols from e-cigarette solvents (vegetable glycerin and propylene glycol) induce bradycardia, bradyarrhythmias, and elevations in heart rate variability during inhalation exposure, with inverse post-exposure effects. These effects are slighter with tobacco- or menthol-flavored aerosols containing nicotine, and in female mice. Yet, menthol-flavored and PG aerosols also increase ventricular arrhythmias and augment early ventricular repolarization (J amplitude), while menthol uniquely alters atrial and atrioventricular conduction. Exposure to e-cigarette aerosols from vegetable glycerin and its byproduct, acrolein, diminish heart rate and early repolarization. The pro-arrhythmic effects of solvent aerosols on ventricular repolarization and heart rate variability depend partly on parasympathetic modulation, whereas ventricular arrhythmias positively associate with early repolarization dependent on the presence of nicotine. Our study indicates that chemical constituents of e-cigarettes could contribute to cardiac risk by provoking pro-arrhythmic changes and stimulating autonomic reflexes.
Seasonally breeding animals concentrate courtship to a particular time of year such that their offspring will be reared in a favorable environment. In house sparrows, Passer domesticus, primary (gonads) and secondary (song, plumage, beak color, etc) sexual characteristics are expressed differentially depending on the photoperiod. Removal of the pineal gland (PINX) has no effect on seasonal rhythms in gonad size but alters the photostimulated increase in vocal rate and complexity. Administration of long durations of melatonin, indicative of short days of winter, prevents seasonal recrudescence of song control nuclei in photostimulated house sparrows. In this study, male PINX house sparrows were exposed to three durations of melatonin, while vocalization and locomotor behavior were recorded as they were transitioned from short photoperiod to equinoctial photoperiods of spring. Birds receiving short duration melatonin or vehicle control increased dawn and dusk choruses as well as call complexity. Long durations of melatonin prevented this expansion to a spring‐like vocal state observed in birds receiving the short duration of melatonin or vehicle control. The daily distribution of locomotor activity, beak color, and testis size was unaffected by treatment. Vocal state change was defined by our measures in two capacities: (i) increased dawn and dusk choruses, and (ii) an increase in calls associated with territory and mate attraction compared to the winter‐like “social song.” We conclude that house sparrows use the calendar information provided by melatonin duration to control seasonal vocalization behavior, independent of effects on and of the gonads.
Background: E-cigarette (e-cig) use has rapidly increased, especially among youth. Vaping has been linked to adverse cardiopulmonary effects, but the full extent of effects remains unknown. Several constituents in e-cigs may increase cardiac risk partly by disturbing cardiac electrophysiology and the autonomic nervous system. Hypothesis: E-cig aerosols will differentially induce pro-arrhythmic changes in cardiac conduction and autonomic balance in mice depending on the presence of nicotine and flavors. Methods: Electrocardiograms (ECGs) were collected by telemetry in 5 healthy male mice (C57BL/6) exposed for 6 hours to clean air or e-cig aerosols (9-minute puff sessions every 18 minutes) from JUUL e-liquids (Va. Tobacco, Mango, or Menthol at ≈5% nicotine benzoate), or a nicotine-free mixture of propylene glycol and vegetable glycerin solvents (PG:VG, 30:70 ratio). ECG morphology, heart rate variability (HRV), and arrhythmias were analyzed by mixed models with P < 0.05 (vs. Air) for all effects. Results: PG:VG increased high grade supraventricular block arrhythmias (121±45 events/hour) relative to Air (0±0 events/hour) and decreased heart rate (HR, -25±8 beats/min), whereas aerosols from all nicotine-containing e-liquids increased HR and decreased HRV, suggesting sympatho-excitation. However, these effects were significantly attenuated for Mango relative to Menthol and Va. Tobacco. As well, only PG:VG and Mango increased ventricular premature beats (VPBs, 9.6±3.7 and 5.5±1.2 events/hour, ±SEM) relative to Air (1.1±0.24 events/hour). VPBs correlated with changes in standard deviation of RR and mean HR from pre-exposure (Spearman’s r : 0.51 and -0.27, P < 0.0001). Prolonged repolarization (QTc) correlated with VPBs during exposures to PG:VG ( r = 0.38, P = 0.046), but not nicotine-containing e-liquids ( r = 0.15, P = 0.38). Conclusions: E-cigs may increase risk for cardiac arrhythmia through e-liquid solvents, which when thermally aerosolized generate toxic aldehydes and particulates. Nicotine and flavor chemicals may modify the cardiac and autonomic impacts of e-cigs. Further studies are needed to determine how e-cig aerosols induce cardiac arrhythmia and whether these effects translate to cardiac morbidity and mortality in humans.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.