Effects of Chronic Nicotine Inhalation on Systemic and Pulmonary Blood Pressure and Right Ventricular Remodeling in Mice.

Introduction:
This text provides an in-depth analysis of a study examining the effects of chronic nicotine inhalation on the cardiopulmonary system, with a focus on systemic and pulmonary blood pressure and cardiac remodeling. The study uses a murine chronic nicotine inhalation model to draw significant conclusions about the potential health risks associated with nicotine inhalation.

Key Points:

* The study exposed C57BL6/J mice to air (control) or nicotine vapor for 8 weeks and monitored serum cotinine levels to assess nicotine exposure.
* Chronic nicotine inhalation led to systemic hypertension, with a maximal effect after 2 weeks and normalization by 4 weeks. however, the BP increase within the first week of nicotine inhalation was sufficiently long to pose potential health risks in individuals with pre-existing cardiopulmonary conditions.
* Chronic nicotine inhalation also resulted in pulmonary hypertension (Ph) with pulmonary vascular and RV remodeling, accompanied by increased RVSP, enhanced expression of BNP in RV protein extracts, and significantly increased Fulton index and PVR.
* Echocardiography revealed RV hypertrophy with increased RV free wall thickness and a trend of increase in RV internal diameter, but no significant structural or functional changes in the LV.
* Immunohistochemistry showed increased muscularization of previously non-muscular pulmonary arterioles in nicotine-exposed mice compared to air-exposed mice, consistent with increased PVR and RVSP.
* The study did not observe significant alteration in alveolar structure or inflammatory cell infiltration in the lung following the 8-week nicotine exposure.
* Nicotine exposure resulted in significant upregulation of aCE expression in the RV, accompanied by activation of the mitogen-activated protein kinases (MaPK) including ERK, p38 and JNK pathways.

Main Message:
The study emphasizes the potential health risks associated with chronic nicotine inhalation, highlighting its effects on both systemic and pulmonary blood pressure and cardiac remodeling. The findings suggest that nicotine exposure alone promotes the development of Ph in the absence of other structural changes commonly observed in COPD. With the increasing popularity of e-cigarettes and newer generations of e-cig formulations, the study underscores the importance of continued nicotine research, public health policies, and awareness of the adverse effects of nicotine inhalation on the cardiopulmonary system.

Oakes JM, Xu J, Morris TM, et al. Effects of Chronic Nicotine Inhalation on Systemic and Pulmonary Blood Pressure and Right Ventricular Remodeling in Mice. hypertension (Dallas, Tex : 1979). 2020;75(5):1305-1314. doi:10.1161/hYPERTENSIONaha.119.14608