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Direct and Acute Cardiotoxicity of Ultrafine Particles in Healthy and Diseased Hearts

Ambient air pollution is associated with increased cardiovascular morbidity and mortality. Previously, ultrafine particles (UFP) were shown to directly and acutely reduce cardiac contractile response in otherwise normal hearts. Their effects on diseased hearts are unknown. Our purpose was to determine the effects of UFP in healthy hearts in relation to hearts with myocardial infarction (MI). Female Sprague‐Dawley rats (200‐250 g) had either a sham operation (SH) or underwent coronary artery occlusion. Three weeks after surgery, the hearts were isolated and Langendorff‐perfused for 30 min with either buffer alone (control) or with UFP extracted from standardized diesel particulate matter (12.5 mg/L). Baseline cardiac contractile function was significantly lower in MI vs. SH (p<0.05, respectively). Thirty‐min data adjusted for baseline differences showed significant reductions in developed pressure (DP), dP/dtmin, and dP/dtmax due to the UFP in both SH and MI groups (p<0.05, respectively). The reduction in function with UFP did not differ between MI and SH. These results are the first to show that direct and acute toxic effects by UFP affect diseased hearts. Since cardiac function is already reduced in hearts with MI, the exposure of these hearts to UFP with further reduction in cardiac function heightens the warning of UFP exposure in coronary patients.