Differential Effects of E-Cigarette on Microvascular Endothelial Function, Arterial Stiffness and Oxidative Stress: A Randomized Crossover Trial

Introduction:
This text is a scientific report on a randomized, placebo-controlled, single-blind crossover trial that examines the effects of e-cigarette vehicles (propylene glycol and glycerol) and nicotine on microcirculatory function, arterial stiffness, hemodynamic parameters, and oxidative stress. The study enrolled 25 healthy occasional tobacco smokers who were exposed to vaping with and without nicotine and sham vaping.

Key Points:

* The study found that vaping with nicotine impairs acetylcholine mediated vasodilation, increases indices of arterial stiffness, raises systolic and diastolic blood pressures and heart rate, and increases plasma myeloperoxidase levels.
* Sham-vaping and vaping without nicotine did not result in any modifications of cardiovascular parameters or oxidative stress.
* Propylene glycol and glycerol carriers did not affect the cardiovascular system, and the observed effects are solely attributable to nicotine.
* The intense vaping conditions used in the study were intended to maximize the ability to detect any harmful effects of e-cigarettes on microcirculation, arterial stiffness, hemodynamic parameters, and oxidative stress.
* Overheated PG/GLY produces free radicals and volatile carbonyls, which are potent vasoconstrictors and oxidative stressors, but the e-cigarette used without nicotine under intense use conditions did not disturb any of the above-mentioned parameters.
* Participants' serum nicotine concentrations after nicotine vaping were similar to those attained after tobacco cigarette smoking or last generation e-cigarettes vaping.
* Nicotine impairs vasodilatation through a PG-dependent rather than a NO-dependent pathway, and this is in agreement with studies where nicotine decreased PG synthesis in the vascular endothelium via an increase in oxidative stress.

Main Message:
The study reveals that high temperature e-cigarette vehicles vaporization and inhalation in occasional smokers does not alter micro and macrovascular endothelial function, as well as oxidative stress. These effects are merely attributable to the nicotine present in the e-liquid, and propylene glycol and glycerol carriers did not affect the cardiovascular system. The intense vaping conditions used in the study were intended to maximize the ability to detect any harmful effects of e-cigarettes, but the e-cigarette used without nicotine under intense use conditions did not disturb any of the above-mentioned parameters. Therefore, the study suggests that e-cigarettes are safer than tobacco smoking, but the use of nicotine-containing e-cigarettes may have adverse cardiovascular effects.

Chaumont, Martin, Benjamin De Becker, Wael Zaher, Antoine Culié, Guillaume Deprez, Christian Mélot, Florence Reyé, et al. “Differential Effects of E-Cigarette on Microvascular Endothelial Function, Arterial Stiffness and Oxidative Stress: A Randomized Crossover Trial.” Scientific Reports 8, no. 1 (July 10, 2018): 10378. https://doi.org/10.1038/s41598-018-28723-0.