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Comparative Electrocardiographic, Autonomic, and Systemic Inflammatory Responses to Soy Biodiesel and Petroleum Diesel Emissions in Rats
Citation:
Farraj, A., N. Coates, D. Winsett, Ian Gilmour, C. King, Todd Krantz, J. Richards, AND M. Hazari. Comparative Electrocardiographic, Autonomic, and Systemic Inflammatory Responses to Soy Biodiesel and Petroleum Diesel Emissions in Rats. INHALATION TOXICOLOGY. Informa Healthcare USA, New York, NY, 27(11):564-75, (2015).
Impact/Purpose:
The purpose of this study was to compare the concentration-dependent effects of repeated exposures to combustion emissions of soy, a model biodiesel fuel, and petroleum diesel in rats.The cardiovascular effects and mechanisms of petroleum diesel exhaust have been thoroughly characterized in experimental models. We have previously shown that exposure causes bradycardia, altered autonomic tone, ST depression, arrhythmia and increases sensitivity to myocardial calcium loading in rats with hypertension or cardiomyopathy. The electrocardiographic and autonomic impacts of exposure to biodiesel emissions, however, are unknown. The findings of this manuscript collectively point to a greater potential for cardiovascular toxicity with exposure to B100 and B0 compared to exposure to B20. While the electrocardiographic analysis revealed few differences with exposure to all three fuel types, there were significant differences in HRV and systemic inflammatory responses among the fuels. Importantly, HRV and serum and plasma analysis revealed that B20 was substantially less toxic than B100 and B0. Taken together, these findings substantiate the emissions data by providing evidence that the reduced pollutant concentrations in the B20 blend are associated with corresponding reductions in cardiovascular toxicity. These findings may reduce uncertainty in risk determinations associated with exposure to both biodiesel and diesel emissions.
Description:
CONTEXT: 8iodiesel fuel represents an alternative to high particulate matter (PM)-emitting petroleum-based diesel fuels, yet uncertainty remains regarding potential biodiesel combustion emission health impacts.OBJECTIVE: The purpose of this study was to compare cardiovascular responses to pure and blended biodiesel fuel emissions relative to petroleum diesel exhaust (DE).MATERIALS AND METHODS: Spontaneously hypertensive rats were exposed for 4 h per day for four days via whole body inhalation to combustion emissions (based on PM concentrations 50, 150 or 500 µg/m(3) or filtered air) from pure (B100) or blended (820) soy biodiesel, or to pure petroleum DE (80). Electrocardiogram (ECG) and heart rate variability (HRV, an index of autonomic balance) were monitored before, during and after exposure while pulmonary and systemic inflammation were assessed one day after the final exposure. ECG and HRV data and inflammatory data were statistically analyzed using a linear mixed model for repeated measures and an analysis of variance, respectively.RESULTS: B100 and BO, but not B20, increased HRV during al exposure days at the highest concentration indicating increased parasympathetic tone. Electrocardiographic data were mixed. 8100 and BO, but not B20, caused significant changes in one or more of the following: serum C-reactive protein, total protein, low density lipoprotein (LDL) and high density lipoprotein (HDL) cholesterol, and blood urea nitrogen (BUN) and plasma angiotensin converting enzyme (ACE) and fibrinogen.DISCUSSION AND CONCLUSIONS: Although responses to emissions from all fuels were mixed and relatively mild, some findings point to a reduced cardiovascular impact of blended biodiesel fuel emissions.
