Acute Cardiovascular Effects in Rats from Exposure to Urban Ambient Particles

Description

Objectives/Hypothesis:

Particulate matter (PM) in ambient air is a complex mixture containing particles of different sizes and chemical composition. Short-term increases in ambient PM levels have been associated with shortterm increases in morbidity and mortality from cardiovascular causes. However, the biologic mechanism by which PM may affect cardiovascular events and the roles of particle size and composition are not well understood. One hypothesis is that particle deposition in the lung induces the release of factors that affect blood cells and vessels throughout the body.

Approach:

The investigators implanted rats with radiotransmitters (to collect continuous data on heart rate, blood pressure, and body temperature) and indwelling catheters for repeated blood sampling. The animals were exposed for 4 hours to clean air or one of four types of resuspended particles: ambient particles (Ottawa dust), ambient particles that had been washed in water to remove soluble components, diesel soot, or carbon black. The investigators used stored resuspended particles rather than fresh particles to ensure that particle concentration and chemical composition were identical among experiments. The investigators measured several endpoints in the rats' blood and plasma (endothelins, nitric oxide products, and catecholamines), changes in heart rate, blood pressure, and general activity, and injury to lung tissue.

Supplemental Keywords:Air, ambient air quality, air toxics, epidemiology, health effects, particulate matter, biochemistry, motor vehicle emissions, diesel exhaust, animal model, Mortality, disease

Relevant Web Sites:

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