A single 10-minute e-cigarette vapor exposure reduces tidal volume and minute ventilation in both normoxia and normobaric hypoxia immediately after exposure

Abstract

This study aimed to investigate the immediate effects of a single exposure of e-cigarette vapor in adult rats on lung function in both normoxia and normobaric hypoxia. We predicted that a single vape exposure would transiently affect lung function in normoxia, but not in hypoxia due to the increase in central respiratory drive during hypoxia. Using random assignment, eighteen adult male Long-Evans rats were assigned to air (control) or vape (experimental) treatment groups. The animals (n=9/group) were exposed to either air or JUUL 5% nicotine vapor using a whole-body exposure chamber for ten minutes. Ventilation in both normoxic and normobaric hypoxic (10% oxygen) conditions was recorded (ten minutes in each condition) the day before treatment (pre-treatment, baseline) and after treatment (post-treatment) using unrestrained whole-body plethysmography. The post-treatment recording occurred immediately after exposure treatment with only thirty seconds of transport time in between the exposure and plethysmography chambers. Blood was collected two hours after the post-treatment ventilation recording to confirm nicotine vapor exposure. Cotinine (a nicotine metabolite) was found to be present in the serum samples of the vapor group (89.2 ± 31.2 ng/mL) but not the air group (0.054 ± 0.052 ng/mL) confirming e-cigarette vapor exposure in the experimental group only (p < 0.001, Student’s t-test). Ventilation parameters frequency, tidal volume, and minute ventilation were individually assessed using 2x2x2 Mixed-Model ANOVA (treatment x time x condition). A main effect of condition (normoxia vs. normobaric hypoxia) on frequency, tidal volume, and minute ventilation (p < 0.001, all three) was observed. All three parameters, frequency, tidal volume, and minute ventilation increased during normobaric hypoxia in both the air and vapor groups. A main effect of time (pre-treatment vs. post-treatment) on tidal volume (p = 0.010) and minute ventilation (p < 0.001) was observed. The vapor group exhibited a lower tidal volume post-treatment in both the normoxic (pre-treatment 0.56 ± 0.083 mL/100g; post-treatment 0.46 ± 0.067 mL/100g) and normobaric hypoxic (pre-treatment 0.77 ± 0.063 mL/100g; post-treatment 0.58 ± 0.065 mL/100g) conditions (p < 0.001). The minute ventilation for the vapor group was also lower post-treatment in both the normoxic (pre-treatment 83.2 ± 16.8 mL/min/100g; post-treatment 59.5 ± 8.75 mL/min/100g) and normobaric hypoxic (pre-treatment 131.5 ± 11.8 mL/min/100g; post-treatment 105.4 ± 15.1 mL/min/100g) conditions (p = 0.002). All data presented as mean ± standard deviation. These data suggest that a single ten minute vapor exposure affects ventilation during the twenty minutes immediately following treatment. Vapor exposure decreased tidal volume, which resulted in a lower minute ventilation in both normoxia and normobaric hypoxia. Future studies will assess the duration of this effect as well as inflammatory cell changes in the air Southwestern University Faculty-Student Project Summer 2022 Grant, Sam Taylor Award 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.