Journal Article

Electrocardiographic Changes during Exposure to Residual Oil Fly Ash (ROFA) Particles in a Rat Model of Myocardial Infarction

Gregory A. Wellenius, Paulo H. N. Saldiva, Joao R. F. Batalha, G. G. Krishna Murthy, Brent A. Coull, Richard L. Verrier and John J. Godleski

in Toxicological Sciences

Volume 66, issue 2, pages 327-335
Published in print April 2002 | ISSN: 1096-6080
Published online April 2002 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/66.2.327
Electrocardiographic Changes during Exposure to Residual Oil Fly Ash (ROFA) Particles in a Rat Model of Myocardial Infarction

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Epidemiological studies have reported a positive association of short-term increases in ambient particulate matter (PM) with daily mortality and hospital admissions for cardiovascular disease. Although patients with cardiopulmonary disease appear to be most at risk, particulate-related cardiac effects following myocardial infarction (MI) have not been examined. To improve understanding of mechanisms, we developed and tested a model for investigating the effects of inhaled PM on arrhythmias and heart rate variability (HRV), a measure of autonomic nervous system activity, in rats with acute MI. Left-ventricular MI was induced in 31 Sprague-Dawley rats by thermocoagulation of the left coronary artery; 32 additional rats served as sham-operated controls. Diazepam-sedated rats were exposed (1 h) to residual oil fly ash (ROFA), carbon black, or room air at 12–18 h after surgery. Each exposure was immediately preceded and followed by a 1-h exposure to room air (baseline and recovery periods, respectively). Lead-II electrocardiograms were recorded. In the MI group, 41% of rats exhibited one or more premature ventricular complexes (PVCs) during the baseline period. Exposure to ROFA, but not to carbon black or room air, increased arrhythmia frequency in animals with preexisting PVCs. Furthermore, MI rats exposed to ROFA, but not to carbon black or room air, decreased HRV. There was no difference in arrhythmia frequency or HRV among sham-operated animals. These results underscore the usefulness of this model for elucidating the physiologic mechanisms of pollution-induced cardiovascular arrhythmias and contribute to defining the specific constituents of ambient particles responsible for arrhythmias.

Keywords: myocardial infarction; particulate matter; arrhythmia; heart rate variability; residual oil fly ash; air pollution; electrocardiogram; Sprague-Dawley rats

Journal Article.  6831 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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