Chronic Exposure to Urban Air Pollution Induces Structural Alterations in Murine Pulmonary and Coronary Arteries

Abstract

Epidemiological studies have shown that air pollution increases cardiovascular morbidity and mortality. Objective markers of cardiovascular risk have also been associated with increases in ambient pollution. This study was designed to assess whether prolonged exposure to ambient levels of air pollution may induce structural alterations of pulmonary and cardiac vessels. Mice were chronically exposed to ambient levels of air pollution in downtown São Paulo, Brazil. The animals were maintained in exposure chambers, 24 h/day, 7 days/wk, during 4 mo. One group was exposed to ambient air, and the control group was exposed to filtered air. Morphometric measurements of the ratio between the lumen and wall (L/W) areas were performed on transverse sections of renal, pulmonary, and coronary arteries. As expected, lumen/wall ratios increased with arterial caliber (p < .001). A significant decrease of L/W with exposure to air pollution was detected in pulmonary (p = .03) and coronary (p = .021) arteries, whereas no effects of air pollution were observed in renal vessels. Our results indicate that animals chronically exposed to ambient air pollution develop a significant thickening of the arterial wall in the coronary and pulmonary circulation.