You are here:
EXPOSURE TO CONCENTRATED AMBIENT PARTICLES IN DETROIT ALTERS HEART RATE VARIABILITY IN SPONTANEOUSLY HYPERTENSIVE RATS
Citation:
Wichers, L. B., J. G. Wagner, J. R. Harkema, M. Morishita, G. J. Keeler, AND A. C. Rohr. EXPOSURE TO CONCENTRATED AMBIENT PARTICLES IN DETROIT ALTERS HEART RATE VARIABILITY IN SPONTANEOUSLY HYPERTENSIVE RATS. Presented at Society of Toxicology Annual Meeting, New Orleans, LA, March 06 - 10, 2005.
Description:
Elevations in airborne particulate matter (PM) are linked to increased mortality and morbidity in humans with cardiopulmonary disease. Clinical studies show that PM is associated with altered heart rate variability (HRV) and suggests that loss of autonomic control may underlie cardiovascular toxicity. To assess the effect of PM on HRV in a rodent model of cardiovascular disease, we exposed spontaneously hypertensive rats (SH) and Wistar-Kyoto (WKY) rats to concentrated air particulates (CAPs) generated from ambient air in urban Detroit. Rats (n=4/group) were exposed to CAPs or filtered Air for 8h/day (7am-3pm), for 13 consecutive days inside a mobile laboratory equipped with whole body exposure chambers and a Harvard type fine concentrator that enriches fine PM (<2.5 m). Rats were implanted with radio transmitters and electrocardiograms were recorded by telemetry. Beat to beat intervals were used to calculate SDNN and RMSSD as determinants of HRV. Average mass concentration of CAPs was 502 + 272 g/m3 (range:103-918). SDNN increased in CAPs/SH rats on Day 1 compared to Air/SH controls (13.5 vs. 15.6 ms; air vs. CAPs), but decreases in SDNN were observed in CAPs/SH rats during successive exposures and were consistent through Day 13 (17.5 + 1.5 vs. 14.9 + 0.5 ms). In CAPs-exposed SH rats, a trend for decreased SDNN in the early morning hours and in the early days of exposure was evident compared to baseline (0.8 - 2.7ms decrease). Conversely, decreased SDNN in the afternoon hours was not present early, but developed by Day 13 in CAPs-SH rats (2.3 ms decrease). CAPs-induced decreases in RMSDD occurred in later exposure days in SH rats. Changes in HRV were not dependent on PM mass. No consistent changes in SDNN or RMSDD were present in CAPs/WKY rats. These data suggest that CAPs-induced changes in HRV in rats with systemic hypertension are dependent on the length and frequency of exposure.
Research supported by EPRI.