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Acute and delayed effects of intermittant ozone on cardiovascular and thermoregulatory responses of young and aged rats
Citation:
Johnstone, A., C. Aydin, R. Macphail, AND C. Gordon. Acute and delayed effects of intermittant ozone on cardiovascular and thermoregulatory responses of young and aged rats. Presented at Society of Toxicology meeting, March 10 - 14, 2013.
Impact/Purpose:
This abstract will be presented at the Society of Toxicology meeting March 10-14, 2013, San Antonio, TX
Description:
Ozone (03) is associated with cardiovascular and respiratory diseases. The aged population is considered to be more sensitive to air pollutants but relatively few studies have demonstrated increased susceptibility in animal models of aging. To study the acute and delayed physiological responses to 03, core temperature (Tc) and heart rate (HR) monitored by telemetry in adult (12 m) and senescent (24 m) Brown Norway rats exposed to intermittent 03 (1.0 ppm, 6 hr/d for 2 consecutive d for 12 wk). Tc and HR dropped precipitously in both age groups during the 1 bout of 03 exposure; Tc decreased from 38 to 35 °C while HR decreased from “300 to ‘175 b/mm. These acute responses were attenuated during the 2nd day of 03. As 03 exposures continued, the acute Tc and HR responses abated but the aged animals were consistently less affected than the young adults throughout the 12 wk exposure period. During 5 d of recovery in home cages, both young and senescent rats displayed a fever-like ‘‘0.5 °C elevation in daytime Tc. HR was also elevated in the young adults during recovery. The rise in Tc persisted for 2-3 d after 03. The 03-induced fever was marked following the l exposure, abated by the 3rd exposure week but then gained in magnitude throughout the remainder of the study. We postulate that inflammatory responses of the respiratory system to 03 are exacerbated in younger animals, leading to accentuated acute physiological responses compared to that of senescent rats. This is an abstract of a proposed presentation and does not reflect US EPA policy.