Concentrated Ambient Particles Alter Myocardial Blood Flow during Acute Ischemia in Conscious Canines

• Published in: Environmental health perspectives Vol. 117; no. 3; pp. 333 - 337
• Main Authors: Bartoli, Carlo R., Wellenius, Gregory A., Coull, Brent A., Akiyama, Ichiro, Diaz, Edgar A., Lawrence, Joy, Okabe, Kazunori, Verrier, Richard L., Godleski, John J.
• Format: Journal Article
• Language: English
• Published: United States National Institute of Environmental Health Sciences. National Institutes of Health. Department of Health, Education and Welfare 01.03.2009; National Institute of Environmental Health Sciences
• Subjects: Air pollution; Analysis; Animals; Arteries; Balloons; Black carbon; Blood flow; Blood pressure; Canines; Catheters; Copyrights; Coronary Circulation - drug effects; Coronary vessels; Crossovers; Dogs; Electrocardiography; Exposure; Health; Health aspects; Inhalation; Ischemia; Mathematical models; Measurement; Microspheres; Models, Biological; Monitoring; Muscle tissues; Myocardial ischemia; Myocardial Ischemia - physiopathology; Myocardium; Occlusion; Oxygen demand; Particle mass; Particles; Particulate Matter - toxicity; Recovery; Vascular resistance; United States; particulate air pollution; myocardial ischemia; myocardial blood flow; microspheres; coronary vasoconstriction
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.11380

Background: Experimental and observational studies have demonstrated that short-term exposure to ambient particulate matter (PM) exacerbates myocardial ischemia. Objectives: We conducted this study to investigate the effects of concentrated ambient particles (CAPs) on myocardial blood flow during myocardial ischemia in chronically instrumented conscious canines. Methods: Eleven canines were instrumented with a ballon occluder around the left anterior descending coronary artery and catheters for determination of myocardial blood flow using fluorescent microspheres. Telemetric electrocardiographic and blood pressure monitoring was available for four of these animals. After recovery, we exposed animals by inhalation to 5 hr of either filtered air or CAPs (mean concentration ± SD, 349.0 ± 282.26 μg/m³) in a crossover protocol. We determined myocardial blood flow during a 5-min coronary artery occlusion immediately after each exposure. Data were analyzed using mixed models for repeated measures. The primary analysis was based on four canines that completed the protocol. Results: CAPs exposure decreased total myocardial blood flow during coronary artery occlusion by 0.12 mL/min/g (p < 0.001) and was accompanied by a 13% (p < 0.001) increase in coronary vascular resistance. Rate-pressure product, an index of myocardial oxygen demand, did not differ by exposure (p = 0.90). CAPs effects on myocardial blood flow were significantly more pronounced in myocardium within or near the ischemic zone versus more remote myocardium (p interaction < 0.001). Conclusions: These results suggest that PM exacerbates myocardial ischemia by increased coronary vascular resistance and decreased myocardial perfusion. Further studies are needed to elucidate the mechanism of these effects.