Arterial stiffness and peripheral chemoreflex responsiveness in electronic cigarette users
Authors: Sayegh Ana Luiza , Faroze Fatima , Paton Julian , Fisher James 
Published: May 2023

Electronic cigarettes (e-cigarettes) are marketed as less harmful alternatives to tobacco smoking, but the short- and long-term health consequences are unclear. Raised arterial stiffness and increased peripheral chemoreflex sensitivity are pathogenic features of several clinical conditions and associated with adverse outcomes. The aim of this study was to determine if regular e-cigarettes use is associated with increased arterial stiffness and elevated peripheral chemoreflex responsiveness.Eight healthy e-cigarettes users (E-cig; >12 months, 6 women, 27±5yr, 26.0±4.5kg/m2 mean±SD) and 13 healthy non-e-cigarettes user controls (HC; 8 women, 26±4yr, 22.4±3.4kg/m2,) were studied under 3 conditions (each for 5min) in the following order: room-air, isocapnic hyperoxia (1.0 fraction of inspired oxygen [FiO2]; peripheral chemoreflex deactivation) and isocapnic hypoxia (0.1 FiO2; peripheral chemoreflex activation). In each condition, arterial stiffness was evaluated by the aortic augmentation index (AIx) and aortic pulse wave velocity (PWV) (SphygmoCor), while heart rate (HR), mean arterial pressure (MAP), and minute ventilation (V̇E) were monitored.In room air, AIx was higher in E-cig compared to HC (18.4±3.4 vs. 8.1±2.5%, P=0.023), while PWV (5.7±0.3 vs. 5.8±0.8m/sec, P=0.731), HR (68±6 vs. 70±9beats/min, P=0.616), MAP (83±4 vs. 83±7mmHg/min, P=0.920), and V̇E (12.7±2.2 vs. 13.9±3.1L/min, P=0.515) were not different. During isocapnic hyperoxia, AIx was unchanged in both E-cig (21.9±11.2%, P=0.327) and HC (9.2±7.9%, P=1.000) versus room air, with AIx remaining higher in E-cig (P=0.006). There were no changes from isocapnic hyperoxia to room air in both E-cig and HC in aortic PWV (Δ0.1±0.1 and Δ0.1±0.2m/sec, P=0.894), HR (Δ-3±3 and Δ-2±3beats/min, P=0.482), MAP (Δ0.3±2.2 and Δ-0.9±2.1mmHg/min, P=0.528) and V̇E (Δ1.1±2.0 vs. Δ1.2±4.6L/min, P=0.124). During isocapnic hypoxia, AIx was unchanged in E-cig (14.7±9.5%, P=0.288) versus room air, but was decreased in HC (2.8±9.4%, P=0.006), such that AIx remained higher in E-cig than HC (P=0.009). HR increased similarly during isocapnic hypoxia in both E-cig (77±7beats/min, P<0.001) and HC (82±7beats/min, P<0.001) compared to room air. In E-cig and HC no change was observed in aortic PWV (Δ0.4±0.4 and Δ0.2±1.4m/sec, P=0.254), MAP (Δ-0.2±2.0 and Δ0.3±2.3mmHg/min, P=0.609) and V̇E (Δ 1.4±1.0 vs. Δ1.1±1.4L/min, P=0.638) during isocapnic hypoxia relative to room air.These preliminary findings suggest that arterial stiffness is higher in young e-cigarettes users, and that the normal hypoxia-induced reduction in arterial stiffness in young non-e-cigarette users is absent in e-cigarettes users. Future studies are needed to determine if the altered effects of hypoxia on arterial stiffness in young e-cigarettes users is associated with exaggerated peripheral chemoreflex mediated sympatho-excitation and/or local endothelial/vascular smooth muscle mechanisms, and if it is reversible on cessation of e-cigarette use. Health Research Council of New Zealand (Ref# 19/687. JPF, JFRP), and the Sidney Taylor Trust (JFRP). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.