Electronic cigarettes Alter cardiac rhythm and heart rate variability hyperacutely in mice

Jocelyn A Castellanos; Carson G Cornett; David H Gonzalez; Liqiao Li; Karla Luna; Holly R Middlekauff; Rajat Gupta; Maria C Jordan; Dennis Rünger; Yifang Zhu; Xuesi Shao; Kenneth P Roos; Jesus A Araujo

doi:10.1016/j.taap.2024.117174

Electronic cigarettes Alter cardiac rhythm and heart rate variability hyperacutely in mice

Toxicol Appl Pharmacol. 2024 Nov 26:117174. doi: 10.1016/j.taap.2024.117174. Online ahead of print.

Authors

Affiliations

¹ Division of Cardiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America; Department of Environmental Health Sciences, Fielding School of Public Health at University of California Los Angeles, Los Angeles, California, United States of America.
² Division of Cardiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America.
³ Department of Environmental Health Sciences, Fielding School of Public Health at University of California Los Angeles, Los Angeles, California, United States of America.
⁴ Department of Physiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America.
⁵ Department of Medicine, Division of General Internal Medicine and Health Services Research, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America.
⁶ Department of Neurobiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America.
⁷ Division of Cardiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, United States of America; Department of Environmental Health Sciences, Fielding School of Public Health at University of California Los Angeles, Los Angeles, California, United States of America; Molecular Biology Institute, University of California Los Angeles, Los Angeles, California, United States of America. Electronic address: JAraujo@mednet.ucla.edu.

PMID: 39608730
DOI: 10.1016/j.taap.2024.117174

Abstract

Aims: There has been an unprecedented rise in electronic cigarette (EC) usage likely because of its perception of being safer than smoking. Recent studies show that EC exposures impact heart rate (HR) and heart rate variability (HRV), but how they are affected by the timing and frequency of exposures remain unclear. We examine the electrocardiographic (EKG) effects induced by brief EC exposures over time, their relation to EC aerosol particle and mass concentrations, and potential to promote prooxidative effects in the lungs.

Methods & results: Six 10-week-old C57BL/6 mice, implanted with telemetry devices to monitor EKG activity continuously, were exposed once per week for three weeks to two EC exposures, each lasting 15-min followed by 45-min post-exposure periods. Filtered air (primary) and PBS (secondary) were used as controls. EC aerosol induced bradycardia and increased time domain parameters during EC exposures with significant reductions in the post-exposure periods. Log-transformed frequency domain parameters were significantly elevated during and after exposures (p < 0.001). HRV changes occurred within minutes with similar trends observed in particle number and mass concentrations of EC aerosol. HR and HRV varied by week and parameter, with Week 2 and 3 effects overshadowing those in Week 1. ECs induced prooxidative effects in the lungs as evidenced by elevated potential for hydroxyl radical generation in bronchoalveolar lavage fluid of exposed mice (p = 0.003).

Conclusion: Short-term EC exposures altered murine HR and HRV within minutes during and after exposures, effects that were modulated by the timing and frequency of EC exposures.

Keywords: Cardiovascular health; Electronic cigarettes; Fine and ultrafine particles and nicotine; Heart rate variability; Oxidative potential; Sinus bradycardia.