Acute and chronic in vivo effects of exposure to nicotine and propylene glycol from an E-cigarette on mucociliary clearance in a murine model

Objective: To determine the effect of an acute (1 week) and chronic (3 weeks) exposure to E-cigarette (E-cig) emissions on mucociliary clearance (MCC) in murine lungs.

Methods: C57BL/6 male mice (age 10.5?±?2.4 weeks) were exposed for 20?min/day to E-cigarette aerosol generated by a Joyetech 510-T^® E-cig containing either 0% nicotine (N)/propylene glycol (PG) for 1 week (n?=?6), or 3 weeks (n?=?9), or 2.4% N/PG for one week (n?=?6), or 3 weeks (n?=?9), followed by measurement of MCC. Control mice (n?=?15) were not exposed to PG alone, or N/PG. MCC was assessed by gamma camera following aspiration of ^99mtechnetium aerosol and was expressed as the amount of radioactivity removed from both lungs over 6?hours (MCC6hrs). Venous blood was assayed for cotinine levels in control mice and in mice exposed for 3-weeks to PG alone and N/PG.

Results: MCC6hrs in control mice and in mice acutely exposed to PG alone and N/PG was similar, averaging (±1 standard deviation) 8.6?±?5.2%, 7.5?±?2.8% and 11.2?±?5.9%, respectively. In contrast, chronic exposure to PG alone stimulated MCC6hrs (17.2?±?8.0)% and this stimulation was significantly blunted following chronic exposure to N/PG (8.7?±?4.6)% (p?Conclusions: In this murine model, a chronic, daily, 20?min-exposure to N/PG, but not an acute exposure, slowed MCC, compared to exposure to PG alone and led to systemic absorption of nicotine.