We found significant differences in respiratory response to CAPs and chronic stress among rats.
Our findings support the hypothesis that chronic stress may exacerbate respiratory response to CAPs air pollution.
As shown in Figure 1, the hemodynamic response to CAPs exhibited considerable dog-to-dog variability.
Respiratory response to CAPs was explored using linear models, predicting respiratory measures during 10-min exposure intervals as a function of animal age, stress exposure duration, and CAPs concentration by stress group.
Because lung function measures were collected concurrently with CAPs/FA exposures, these acute responses in the nonstress group may offset some observable effects of the chronic stress paradigm and may alter short-term response to CAPs in nonstressed animals.
However, we observed significant CAPs-by-prazosin interactions for pulse pressure, heart rate, and rate pressure product (p < 0.02 for each), suggesting that α-adrenergic blockade modified the response to CAPs for these parameters.
Similar to data from study B, subjects in study A demonstrated a statistically significant increase in DBP (1.97 mmHg, p = 0.02) in response to CAPs + O3. Figure 4 shows DBP at 30-min intervals throughout the exposure period.
Our previous work indicates that significant disruption of adulthood neurotransmission in response to CAPs exposure in mice persists at least to almost 1 year of age (Allen et al. 2014a, 2014b).
In spite of these limitations, as the first controlled exposure study of this type, the present study reports statistically significant differences between the response to CAPs and filtered air under each of the three dietary regimens for several important outcomes.
More exposure days are needed to understand effects of longer-term stress and pollution exposures on health; currently, the critical number of days required to establish "chronic" stress physiologic conditions, or to fully capture trends in respiratory response to CAPs, remains unknown.
Although the absolute magnitude of the average change in blood pressure in response to CAPs may appear small (on the order of 2 4 mmHg), such an increase applied over time to a large population could have important public health consequences, as documented by results from multiple large prospective cohorts (Kannel et al. 2003).
