Cardiovascular effects of diesel exhaust inhalation: photochemically altered versus freshly emitted in mice

Abstract

This study was designed to compare the cardiovascular effects of inhaled photochemically-altered diesel exhaust (aged DE) to freshly-emitted DE (fresh DE) in female C57Bl/6 mice. Mice were exposed to either fresh DE, aged DE, or filtered air (FA) for 4 hr using an environmental irradiation chamber. Cardiac responses were assessed 8 hr after exposure utilizing Langendorff preparation with a protocol consisting of 20 min of perfusion and 20 min of ischemia followed by 2 hr of reperfusion. Cardiac function was measured by indices of left-ventricular developed pressure (LVDP) and contractility (dP/dt) prior to ischemia. Recovery of post-ischemic LVDP was examined on reperfusion following ischemia. Fresh DE contained 460 μg/m 3 of particulate matter (PM), 0.29 ppm of nitrogen dioxide (NO 2) and no ozone (O 3), while aged DE consisted of 330 μg/m 3 of PM, 0.23 ppm O 3 and no NO 2. Fresh DE significantly decreased LVDP, dP/dt max , and dP/dt min compared to FA. Aged DE also significantly reduced LVDP and dP/dt max. Data demonstrated that acute inhalation to either fresh or aged DE lowered LVDP and dP/dt, with a greater fall noted with fresh DE, suggesting that the composition of DE may play a key role in DEinduced adverse cardiovascular effects in female C57Bl/6 mice.