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BACKGROUND: The cardiopulmonary effects of the individual criteria air pollutants have been well investigated, but little is known about the cardiopulmonary effects of inhaled multi-pollutant mixtures that more realistically represent environmental exposures.

OBJECTIVES: We assessed the cardiopulmonary effects of exposure to photochemically altered particle-free multi-pollutant mixtures.

METHODS: We exposed mice to filtered air (FA), multi-pollutant mixtures, or ozone (O-3) for 4 hr in a photochemical reaction chamber. Eight hours after exposure, we assessed cardiac responses using a Langendorff preparation in a protocol consisting of 20 min of global ischemia followed by 2 hr of reperfusion. Cardiac function was assessed by measuring the index of left-ventricular developed pressure (LVDP) and contractility (dP/dt) before ischemia. On reperfusion after ischemia, recovery of post-ischemic LVDP and size of infarct were examined. We used bronchoalveolar lavage (BAL) cell counts to assess lung inflammation.

RESULTS: Exposure to the multi-pollutant mixtures decreased LVDP, baseline rate of left ventricular contraction (dP/dt(maximum)), and baseline rate of left ventricular relaxation (dP/dt(minimum)) compared with exposure to FA. Exposure to O-3 also decreased heart rate and dP/dt(minimum). Time to ischemic contracture was prolonged in the multi-pollutant-mixture group relative to that in the FA group. Mice in the multi-pollutant-mixture group had better recovery of post-ischemic LVDP and smaller infarct size. Exposure to multi-pollutant mixtures and to O-3 exposure increased numbers of macrophages in the BAL fluid.

CONCLUSIONS: Exposure to photochemically altered urban air pollution appears to affect cardiac mechanics in isolated perfused hearts. Inhalation of acute multi-pollutant mixtures decreases LVDP and cardiac contractility in isolated non-ischemic murine hearts, prolongs ischemic contracture, increases post-ischemic recovery of LVDP, and reduces infarct size.