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/m³ of particulate matter (PM), 0.29 ppm of nitrogen dioxide (NO₂) and no ozone (O₃), while aged DE consisted of 330 µg/m³ of PM, 0.23 ppm O₃ and no NO₂. 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 DE-induced adverse cardiovascular effects in female C57Bl/6 mice.

KEYWORDS:

• Diesel exhaust
• photochemistry
• cardiac function

Acknowledgments

The U.S. Environmental Protection Agency Intramural Research Program supported this research. This work was also supported in part by the U.S. Environmental Protection Agency Cooperative Agreement CR83346301 with the Center for Environmental Medicine, Asthma and Lung Biology at the University of North Carolina at Chapel Hill. The authors thank Corey Jana for excellent technical assistance in the execution of this study. We are grateful to Dr. Stephen Gavett for critical review of this manuscript.

Competing Financial Interest Declaration

The authors declare that they have no actual or potential competing financial interests.

Disclaimer

The research described in this article has been reviewed by the National Health and Environmental Effects Research Laboratory, U.S. EPA, and approved for publication. The contents of this article should not be construed to represent Agency policy nor does mention of trade names or commercial products constitute endorsement or recommendation for use.

Additional information

Funding

This work was supported by The U.S. Environmental Protection Agency Intramural Research Program .