Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108, USA.
Environ Health Perspect. 2011 Aug;119(8):1136-41. doi: 10.1289/ehp.1003101. Epub 2011 Apr 25.
The composition of diesel engine exhaust (DEE) varies by engine type and condition, fuel, engine operation, and exhaust after treatment such as particle traps. DEE has been shown to increase inflammation, susceptibility to infection, and cardiovascular responses in experimentally exposed rodents and humans. Engines used in these studies have been operated at idle, at different steady-state loads, or on variable-load cycles, but exposures are often reported only as the mass concentration of particulate matter (PM), and the effects of different engine loads and the resulting differences in DEE composition are unknown.
We assessed the impacts of load-related differences in DEE composition on models of inflammation, susceptibility to infection, and cardiovascular toxicity.
We assessed inflammation and susceptibility to viral infection in C57BL/6 mice and cardiovascular toxicity in APOE-/- mice after being exposed to DEE generated from a single-cylinder diesel generator operated at partial or full load.
At the same PM mass concentration, partial load resulted in higher proportions of particle organic carbon content and a smaller particle size than did high load. Vapor-phase hydrocarbon content was greater at partial load. Compared with high-load DEE, partial-load DEE caused greater responses in heart rate and T-wave morphology, in terms of both magnitude and rapidity of onset of effects, consistent with previous findings that systemic effects may be driven largely by the gas phase of the exposure atmospheres. However, high-load DEE caused more lung inflammation and greater susceptibility to viral infection than did partial load.
Differences in engine load, as well as other operating variables, are important determinants of the type and magnitude of responses to inhaled DEE. PM mass concentration alone is not a sufficient basis for comparing or combining results from studies using DEE generated under different conditions.
柴油机排气（DEE）的组成因发动机类型和状况、燃料、发动机运行以及颗粒捕集器等尾气后处理而有所不同。研究表明，DEE 会增加实验暴露的啮齿动物和人类的炎症、易感性和心血管反应。这些研究中使用的发动机在怠速、不同稳态负载或变负载循环下运行，但暴露通常仅报告为颗粒物（PM）的质量浓度，不同发动机负载的影响以及由此产生的 DEE 组成差异尚不清楚。
我们评估了 DEE 组成与负载相关的差异对炎症、易感性感染和心血管毒性模型的影响。
我们评估了 C57BL/6 小鼠在暴露于部分或全负荷运行的单缸柴油机产生的 DEE 后炎症和易感性感染模型以及 APOE-/- 小鼠的心血管毒性。
在相同的 PM 质量浓度下，部分负荷比高负荷产生更高比例的颗粒有机碳含量和更小的颗粒尺寸。部分负荷时蒸气相烃含量更高。与高负荷 DEE 相比，部分负荷 DEE 导致心率和 T 波形态的反应更大，无论是效应的起始幅度还是速度，这与先前的研究结果一致，即全身效应可能主要由暴露气氛的气相驱动。然而，高负荷 DEE 引起的肺部炎症和易感性感染比部分负荷更大。
发动机负载以及其他操作变量的差异是决定吸入 DEE 反应类型和程度的重要因素。PM 质量浓度本身不足以作为比较或合并在不同条件下产生的 DEE 研究结果的基础。
