| Air pollution, including particulate matter (PM), is known to cause increases in respiratory and cardiovascular morbidity and mortality. The elderly are considered one of the most susceptible groups. However, the specific effects of PM exposure and the mechanisms that lead to greater risk in the elderly are still largely unknown.;The purpose of this thesis was to investigate the interactive effects of acute PM exposure and aging. Using mouse models, clinically relevant measures of the pulmonary and cardiac systems, which were airway reactivity (AR), heart rate (HR) and heart rate variability (HRV), were used. Additional parameters were collected to understand other potential systemic effects of PM exposure. The measurements were collected in several different age groups representing young, mid-life, and older adults. The mice were exposed to carbon black by inhalation or PM collected in Baltimore, Maryland by instillation.;The results indicated that PM exposure caused age-dependent differences. The young mice were under-responsive to changes in AR, HR, and HRV. AR increased in the mid-life mice at twenty-four hours after exposure to carbon black. When mid-life mice were exposed to PM, there were two distinct patterns of responses, responsive and non-responsive , as measured by changes in HR and HRV. The oldest mice were non-responsive to PM exposure.;It has been hypothesized that these differences in response patterns could be due to changes in organ system function, which occurs as part of the aging process. This loss of function can be empirically quantified by assessing the loss of complexity in specific physiological systems. As loss of complexity occurs, it results in fewer compensatory mechanisms to maintain homeostasis. Data collected supported the hypothesis that the non-responsiveness of the older mice was likely due to a loss of complexity, as measured by the variance in HR.;Better understanding of the compensatory mechanisms to PM exposure is useful in developing preventive measures for the elderly to further reduce morbidity and mortality after PM exposure. Overall, the differences in compensatory responses to PM exposure between the age groups may help to explain why some age groups are more at-risk for increased morbidity and mortality. |
