Exercise training prevented endothelium dysfunction from particulate matter instillation in Wistar rats

Exposure to fine particulate matter (PM_2.5) can result in adverse cardiovascular responses including vascular endothelial dysfunction, whereas exercise training can promote cardiovascular health. However, whether exercise training can mitigate adverse vascular response to PM_2.5 has been less studied. In the present study, we aimed to investigate the preventive effect of exercise training on vascular endothelial dysfunction induced by PM_2.5 instillation. Six-week old male Wistar rats (n = 32) were divided into four groups (8 rats per group) by exercise status (sedentary vs. exercised) and PM_2.5 exposure (instilled vs. non-instilled). Rats received treadmill training with moderate-intensity intervals in week 1 to 6, followed by three repeated PM_2.5 instillation on every other day in week 7. Body weight and blood pressure were measured for each rat regularly during exercise training and before sacrifice. At sacrifice, thoracic aortas were isolated for functional response measurement to agonists. Nitric oxide bioavailability and high-density lipoprotein (HDL) function were also assessed. We observed that exercise training significantly reduced the body weight of rats, while PM_2.5 instillation had little effect. Neither exercise training nor PM_2.5 instillation had significant effects on blood pressure changes. However, exercise training effectively prevented endothelium-dependent vasorelaxation dysfunction and nitric oxide bioavailability reduction from subsequent PM_2.5 instillation. In addition, exercise training promoted HDL function which were characterized as increased HDL cholesterol level, cholesterol efflux capacity, and reduced oxidization index; whereas PM_2.5 instillation showed limited adverse impact on HDL function. Collectively, our results indicated that exercise training could promote HDL function and protect against endothelium dysfunction from PM_2.5 instillation.