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Time‐dependent decrease in heart rate variability to particulate matter exposure in mice
Author(s) -
Chen ChaoYin,
Pinkerton Kent E,
Bonham Ann C
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a473-d
Subject(s) - heart rate variability , acute exposure , particulates , chemistry , heart rate , analysis of variance , medicine , endocrinology , zoology , biology , blood pressure , organic chemistry
Exposure to PM2.5 increases the total daily cardiovascular mortality by an estimated 3–4% for every 25 μg/m 3 increase in PM2.5. Impaired cardiac autonomic function, indexed by reduced heart rate variability (HRV), is one underlying cause. We previously showed that 3 d (6 hr/d) of sidestream smoke, a major indoor PM2.5 pollutant, reduced HRV in mice. Here, we hypothesized that PM2.5 mediates the short‐term (3‐d) exposure‐induced reduced HRV. HRV parameters were measured in time domain over 48 hr in mice after 3 d (6 hr/d) of exposure to either filtered air (FA) or PM2.5 (iron/soot) generated from a true combustion source. There were four exposure groups: FA (n=10), soot only (n=11; TSP = 224 ± 9 μg/m 3 ), low iron (n = 13; TSP = 213 ± 7 μg/m 3 ; 16 ± 2% iron), and high iron (n = 8; TSP = 215 ± 19 μg/m 3 ; 34 ± 5% iron). PM2.5 exposure significantly decreased HRV during the first 24 hr after exposure (2 way ANOVA, p < 0.05 exposure effect). The decrease in HRV was greater during 24–48hr after exposure (2 way ANOVA, p < 0.05 time effect) consistent with human studies showing a lag‐time between increases in ambient PM concentration and the occurrence of cardiovascular events. The data suggest that the PM2.5 mediates the exposure‐induced reduction in HRV and the exposure effect is time‐dependent. These results provide evidence for the importance of regulating air quality on improving cardiovascular health. (Support: EPA 008045, 1R01ES012957)