Direct and acute cardiotoxicity of ultrafine particles in young adult and old rat hearts
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Air pollution is associated with significant increases in cardiac morbidity and mortality in the general population. The elderly cohort within the general population is considered at high risk for cardiac diseases. However the degree to which air pollutants affect cardiac responses in old hearts vs. their young adult counterparts has not been systematically addressed.
We sought to investigate the response of young adult vs. old rat hearts to the direct exposure of ultrafine particles (UFP); i.e. when the UFP are directly instilled into the cardiac vasculature, and their effects are not dependent upon UFP inhalation.
The study was performed in isolated Langendorff-perfused rat hearts obtained from young adult (4 months old) and aged (26 months old) Fisher 344/Brown Norway rats. Two treatment groups (control and UFP-treated) were studied, and two ages (young adult and old) were studied within each group. Control hearts were perfused with buffer only, UFP-treated hearts were perfused with buffer containing ultrafine particles isolated from industrial diesel reference particulate matter. Systolic and end-diastolic pressures, positive and negative dP/dt, and coronary flow were measured.
Young adult and old hearts demonstrated equal functional deterioration in response to direct infusion of UFP. Developed pressure in young adult UFP-treated hearts fell from 101±4 to 68±8 mmHg (a decrease by 33%, p<0.05). In the old UFP-treated hearts developed pressure fell by 35% (from 101±7 to 67±9mmHg, p<0.05). Positive dP/dt was equally affected in the young adult and old UFP-treated hearts and was decreased by 28% in both groups.
Ultrafine particles when instilled directly into the cardiac vasculature were equally cardiotoxic in young adult and old rat hearts.
Key wordsair pollution ultrafine particles cardiotoxicity
industrial diesel reference particulate matter
National Institute of Standards and Technology
young adult control hearts
old control hearts
young adult hearts treated with ultrafine particles
old hearts treated with ultrafine particles
reactive oxygen species
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