Research

Exposure to ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats

Swapna Upadhyay¹ , Tobias Stoeger¹ , Volkar Harder¹ , Ronald F Thomas² , Mette C Schladweiler² , Manuela Semmler-Behnke¹ , Shinji Takenaka¹ , Erwin Karg¹ , Peter Reitmeir³ , Michael Bader⁴ , Andreas Stampfl⁵ , Urmila P Kodavanti² and Holger Schulz¹

¹  Institute for Inhalation Biology, HelmholtzZentrum München, German Research Center for Environmental Health, Neuherberg, Germany

²  EPA-NHEERL, Research Triangle Park, NC 27709, USA

³  Institute of Health Economics and Health Care Management, HelmholtzZentrum München, German Research Center for Environmental Health, Neuherberg, Germany

⁴  Molecular Biology of Peptide Hormones, Max Delbrück Center for Molecular Medicine, Berlin, Germany

⁵  Institute of Toxicology, HelmholtzZentrum München, German Research Center for Environmental Health, Neuherberg, Germany

author email corresponding author email

Particle and Fibre Toxicology 2008, 5:19doi:10.1186/1743-8977-5-19

Published:	4 December 2008

Abstract

Background

Exposure to particulate matter is a risk factor for cardiopulmonary disease but the underlying molecular mechanisms remain poorly understood. In the present study we sought to investigate the cardiopulmonary responses on spontaneously hypertensive rats (SHRs) following inhalation of UfCPs (24 h, 172 μg·m^-3), to assess whether compromised animals (SHR) exhibit a different response pattern compared to the previously studied healthy rats (WKY).

Methods

Cardiophysiological response in SHRs was analyzed using radiotelemetry. Blood pressure (BP) and its biomarkers plasma renin-angiotensin system were also assessed. Lung and cardiac mRNA expressions for markers of oxidative stress (hemeoxygenase-1), blood coagulation (tissue factor, plasminogen activator inhibitor-1), and endothelial function (endothelin-1, and endothelin receptors A and B) were analyzed following UfCPs exposure in SHRs. UfCPs-mediated inflammatory responses were assessed from broncho-alveolar-lavage fluid (BALF).

Results

Increased BP and heart rate (HR) by about 5% with a lag of 1–3 days were detected in UfCPs exposed SHRs. Inflammatory markers of BALF, lung (pulmonary) and blood (systemic) were not affected. However, mRNA expression of hemeoxygenase-1, endothelin-1, endothelin receptors A and B, tissue factor, and plasminogen activator inhibitor showed a significant induction (~2.5-fold; p < 0.05) with endothelin 1 being the maximally induced factor (6-fold; p < 0.05) on the third recovery day in the lungs of UfCPs exposed SHRs; while all of these factors – except hemeoxygenase-1 – were not affected in cardiac tissues. Strikingly, the UfCPs-mediated altered BP is paralleled by the induction of renin-angiotensin system in plasma.

Conclusion

Our finding shows that UfCPs exposure at levels which does not induce detectable pulmonary neutrophilic inflammation, triggers distinct effects in the lung and also at the systemic level in compromised SHRs. These effects are characterized by increased activity of plasma renin-angiotensin system and circulating white blood cells together with moderate increases in the BP, HR and decreases in heart rate variability. This systemic effect is associated with pulmonary, but not cardiac, mRNA induction of biomarkers reflective of oxidative stress; activation of vasoconstriction, stimulation of blood coagulation factors, and inhibition of fibrinolysis. Thus, UfCPs may cause cardiovascular and pulmonary impairment, in the absence of detectable pulmonary inflammation, in individuals suffering from preexisting cardiovascular diseases.