Concentrated ambient air particles induce vasoconstriction of small pulmonary arteries in rats.

Abstract

The objective of this study was to determine whether short-term exposures to concentrated ambient particles (CAPs) alter the morphology of small pulmonary arteries in normal rats and rats with chronic bronchitis (CB). Sprague-Dawley male rats were exposed to CAPs, using the Harvard Ambient Particle Concentrator, or to particle-free air (sham) under identical conditions during 3 consecutive days (5 hr/day) in six experimental sets. CB was induced by exposure to 276 +/- 9 ppm of sulfur dioxide (5 hr/day, 5 days/week, 6 weeks). Physicochemical characterization of CAPs included measurements of particle mass, size distribution, and composition. Rats were sacrificed 24 hr after the last CAPs exposure. Histologic slides were prepared from random sections of lung lobes and coded for blinded analysis. The lumen/wall area (L/W) ratio was determined morphometrically on transverse sections of small pulmonary arteries. When all animal data (normal and CB) were analyzed together, the L/W ratios decreased as concentrations of fine particle mass, silicon, lead, sulfate, elemental carbon, and organic carbon increased. In separate univariate analyses of animal data, the association for sulfate was significant only in normal rats, whereas silicon was significantly associated in both CB and normal rats. In multivariate analyses including all particle factors, the association with silicon remained significant. Our results indicate that short-term CAPs exposures (median, 182.75 micro g/m3; range, 73.50-733.00 micro g/m3) can induce vasoconstriction of small pulmonary arteries in normal and CB rats. This effect was correlated with specific particle components and suggests that the pulmonary vasculature might be an important target for ambient air particle toxicity.

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“…1). Most notably, several studies in humans and animals have shown significant arterial vasoconstriction following PM inhalation [28,37]. The altered autonomic balance may be playing a direct role in mediating this vasoconstriction and thereby the BP elevation.…”

Mechanisms mediating adverse effects of air pollution on cardiovascular hemodynamic function and vulnerability to cardiac arrhythmias

“…The importance of considering CAPs composition rather than CAPs mass concentration has been highlighted in several reports from our laboratory (Clarke et al 2000b;Batalha et al 2002;Saldiva et al 2002). ST-segment elevation was found to be related to a specific component Fig.…”

“…For example, in CAPs-exposed dogs, increases in bronchoalveolar lavage neutrophil percentage, circulating neutrophils and lymphocytes, and total peripheral white blood cell counts were significantly associated with an aluminum/silicon factor (Clarke et al 2000a). Batalha et al (2002) observed that the degree of pulmonary vascular vasoconstriction was strongly correlated with the elemental concentration of silicon in normal and bronchitic rats exposed to CAPs. These observations suggested that components of ambient particles whose concentrations vary in parallel with the concentration of silicon may be highly toxic.…”

Effects of Nanoparticles on the Pulmonary Vasculature

“…Children exposed to ambient PM demonstrate elevated plasma ET -1 and mean pulmonary arterial pressure (Calderon -Garciduenas et al, 2007 ). Inhalation of urban PM has been demonstrated to increase vascular tone in small pulmonary arterioles (Batalha et al, 2002 ). This process appears, in part, to be a consequence of altered NO -mediated vasorelaxation.…”