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Inhalation of Simulated Smog Affects Cardiac Function in Mice
Citation:
Tong, H., Todd Krantz, M. McGee, J. Krug, C. King, AND S. Gavett. Inhalation of Simulated Smog Affects Cardiac Function in Mice. Society of Toxicology, New Orleans, LA, March 13 - 17, 2016.
Impact/Purpose:
This study assesses the cardiovascular effects of simulated smog inhalation in mice. The particular simulated smog had high organic carbon and low particulate matter content. After smog exposure, the baseline cardiac function and contractility was decreased in a mouse model.
Description:
Rationale: The health effects of individual criteria air pollutants have been well investigated. Little is known about health effects of inhaled multi-pollutant mixtures that more realistically represent environmental exposures. The present study was designed to evaluate the cardiac effects of inhaled simulated smog mixture in a murine model. Methods: Four-month old female C57/Bl6J mice were exposed for 4 hours to filtered air (FA) or simulated smog generated by mixture of 15 ppm hydrocarbon and 900 ppb NO gas in the presence of UV light. Final exposure conditions consisted of 53 µg/m3 secondary organic aerosol (SOA), 0.376 ppm O3, and 0.617 ppm NO2. Immediately and 20 hr after exposure, cardiac responses were assessed with a Langendorff preparation using a protocol consisting of 20 min of global ischemia followed by 2 hr reperfusion. Cardiac function was measured by index of left-ventricular developed pressure (LVDP) and contractility (dP/dtmax and dP/dtmin) before ischemia. On reperfusion after ischemia, recovery of post-ischemic LVDP and infarct size were examined. Results: Baseline LVDP and dP/dtmax were lower in the mice 20 hr after the simulated smog exposure compared to the FA control. Baseline LVDP was also decreased immediately after smog exposure. However, there was no statistically significant difference of post-ischemic recovery of cardiac function and infarct size between the smog and FA groups at either time points. In addition, smog exposure reduced the coronary artery flow rate compared to the FA control. Heart rate was not affected by the exposure. Conclusions: This study demonstrated that acute smog exposure decreases baseline LVDP, cardiac contractility, and coronary flow rate in mice, indicating that photochemically-altered atmosphere affects the cardiovascular system. (This abstract does not necessarily reflect EPA policy.)