Ambient airborne particles with an aerodynamic diameter of <2.5 µm (PM2.5), which contain particles from combustion processes, are linked to increased risks for cardiovascular and respiratory diseases. In this experimental study, the short-term and long-term physiologic consequences of PM2.5 inhalation were investigated with the focus on inflammatory parameters and vascular tonus. PM2.5 collected from urban environments in southern Sweden were aerosolized with a nebulizer and delivered to male Sprague Dawley rats. The rats were divided into two treatment groups (n=8 in each): short-term exposed (8 h with an estimated lung exposure rate of 90 μg PM2.5/h); and long-term exposed (3 h/day, 5 days/week, for 8 weeks, with an estimated lung exposure rate of 30 μg PM2.5/h). A group of non-particle-exposed control animals (n=8) was run in parallel with each test group. The results showed that short-term exposure increased the numbers of lymphocytes in the bronchoalveolar lavage fluids. Long-term exposure led to impaired substance P-induced relaxation and increased endothelin-1-induced contraction of the coronary arteries. The contractile response was found to be mediated by endothelin receptor A. Long-term exposure led to increased interleukin-6 levels in brain tissues, as compared to the controls. In summary, this explorative study reveals that exposure to aerosolized, ambient PM2.5 leads to impaired coronary artery function and neuroinflammation. Further investigations into the impacts on health effects of short-term and long-term exposures to urban air pollution are warranted.
- Miljömedicin och yrkesmedicin