Journal Article

Effects of Ozone and Particulate Matter on Cardiac Mechanics: Role of the Atrial Natriuretic Peptide Gene

Clarke G. Tankersley, Dimitrios Georgakopoulos, Wan-Yee Tang, Eric Abston, Alexis Bierman and Nicole Sborz

in Toxicological Sciences

Volume 131, issue 1, pages 95-107
Published in print January 2013 | ISSN: 1096-6080
Published online September 2012 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/kfs273
Effects of Ozone and Particulate Matter on Cardiac Mechanics: Role of the Atrial Natriuretic Peptide Gene

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A positive association between air pollution exposure and increased human risk of chronic heart disease progression is well established. In the current study, we test two hypotheses: (1) the cardiac compensatory changes in response to air pollution are dependent on its composition and (2) specific cardiac adaptations are regulated by atrial natriuretic peptide (ANP). We address these hypotheses by initially examining the exposure effects of ozone (O3) and/or particulate matter (PM) on cardiac function in C57Bl/6J (B6) mice. Subsequently, the results are compared with cardiac functional changes to the same exposures in Nppa (the precursor gene for ANP) knockout (KO) mice. Separate groups of mice underwent 3 consecutive days of the same exposure sequence for 3h each consisting of the following: (1) 6h of filtered air (FAFA), (2) O3 then FA (O3FA), (3) FA then carbon black (FACB), or (4) O3 then CB. Cardiac function was assessed using a conductance catheter to generate cardiac pressure-volume loops 8–10h following each exposure sequence. As compared with FAFA, each sequence led to a substantial drop (as much as 33%) in stroke volume and cardiac output. However, these losses of cardiac function occurred by different compensatory mechanisms dependent on the pollutant composition. For example, O3FA exposure led to reductions in both end-systolic and end-diastolic left ventricular (LV) volumes, whereas FACB exposure led an increase in end-diastolic LV volume. These same cardiac compensatory changes were largely abolished in Nppa KO mice following O3FA or FACB exposure. These results suggest that cardiac functional changes in response to air pollution exposure are strongly dependent on the pollutant constituents, especially related to O3 and/or PM. Furthermore, ANP regulation appears to be crucial to these cardiac compensatory mechanisms induced by air pollution.

Keywords: air pollution; atrial natriuretic peptide; cardiac structure and function; cardiopulmonary regulation; in vivo hemodynamics

Journal Article.  9093 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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