Increased non-conducted P-wave arrhythmias after a single oil fly ash inhalation exposure in hypertensive rats.
BACKGROUND
Exposure to combustion-derived fine particulate matter (PM) is associated with increased cardiovascular morbidity and mortality especially in individuals with cardiovascular disease, including hypertension. PM inhalation causes several adverse changes in cardiac function that are reflected in the electrocardiogram (ECG), including altered cardiac rhythm, myocardial ischemia, and reduced heart rate variability (HRV). The sensitivity and reliability of ECG-derived parameters as indicators of the cardiovascular toxicity of PM in rats are unclear.


OBJECTIVE
We hypothesized that spontaneously hypertensive (SH) rats are more susceptible to the development of PM-induced arrhythmia, altered ECG morphology, and reduced HRV than are Wistar Kyoto (WKY) rats, a related strain with normal blood pressure.


METHODS
We exposed rats once by nose-only inhalation for 4 hr to residual oil fly ash (ROFA), an emission source particle rich in transition metals, or to air and then sacrificed them 1 or 48 hr later.


RESULTS
ROFA-exposed SH rats developed non-conducted P-wave arrhythmias but no changes in ECG morphology or HRV. We found no ECG effects in ROFA-exposed WKY rats. ROFA-exposed SH rats also had greater pulmonary injury, neutrophil infiltration, and serum C-reactive protein than did ROFA-exposed WKY rats.


CONCLUSIONS
These results suggest that cardiac arrhythmias may be an early sensitive indicator of the propensity for PM inhalation to modify cardiovascular function.
Farraj
Aimen K
AK
Experimental Toxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA. farraj.aimen@epa.gov
Haykal-Coates
Najwa
N
Winsett
Darrell W
DW
Hazari
Mehdi S
MS
Carll
Alex P
AP
Rowan
William H
WH
Ledbetter
Allen D
AD
Cascio
Wayne E
WE
Costa
Daniel L
DL
D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced*; D002244:Carbon / Q000633:toxicity*; D060729:Coal Ash; D004562:Electrocardiography; D006339:Heart Rate / Q000187:drug effects; D019570:Inhalation Exposure; D008297:Male; D052638:Particulate Matter / Q000633:toxicity*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000393:Air Pollutants; D060729:Coal Ash; D052638:Particulate Matter; D002244:Carbon