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Aging and episodic ozone exposure in Brown Norway rats: Effects on heart rate, core temperature, pulmonary function, and expression of serum biomarkers.
Citation:
GORDON, C. J., J. Schmid, J. R. LEHMANN, A. D. LEDBETTER, A. F. JOHNSTONE, W. Ward, M. SCHLADWEILER, U. P. KODAVANTI, AND R. C. MACPHAIL. Aging and episodic ozone exposure in Brown Norway rats: Effects on heart rate, core temperature, pulmonary function, and expression of serum biomarkers. Presented at Society of Toxicology (SOT) Annual Meeting, San Francisco, CA, March 11 - 15, 2012.
Impact/Purpose:
Ozone (03) is an air pollutant that is associated with cardiovascular and respiratory diseases. The aged population is considered to be more sensitive to pollutants such as 03; however, relatively few studies have demonstrated increased susceptibility in aged or senescent animal models.
Description:
Ozone (03) is an air pollutant that is associated with cardiovascular and respiratory diseases. The aged population is considered to be more sensitive to pollutants such as 03;however, relatively few studies have demonstrated increased susceptibility in aged or senescent animal models. We employed a subchronic, intermittent 0 3 exposure protocol to study the susceptibility in young and aged Brown Norway (BN) rats. In one study, young adult (4 m) and aged (20 m) rats were exposed to 0 or 0.8ppm 03 for 6 hr/d, 1 d/wk for 17 wks. Respiratory parameters assessed by unrestrained plethysmography the day after exposure revealed that 03 led to airway-flow limitation (i.e. increased PenH). Young rats exhibited a greater rise in PenH over the 17 wk exposure. Bronchoalveolar fluid macrophages were reduced in aged rats and neutrophils increased in young rats. Age affected 20 of 58 serum analytes, including C-reactive protein, interferon, and macrophage inflammatory protein-2 (MIP-2). 03 affected 6 analytes, including fibroblast growth factor (basic), MIP-2, leukemia inhibitor factor, and haptoglobin. In another study, core temperature (Tc) and heart rate (HR) were monitored by telemetry in 8 and 20 m BN rats exposed for 6 hr/d, 2 consecutive dlwk to 0 or 1.0 ppm 03 for 12 wk. Aged rats were less sensitive to the hypothermic and bradycardic effects of 03. Recovery from 03 was characterized by a fever persisting for several days, with recovery of aged animals prolonged. Overall, the acute physiological effects of 03 are manifested more in younger animals while recovery for Tc and HR and expression of certain serum biomarkers is worsened with age. This is an abstract of a proposedpresentation and does not reflect US EPA policy