Research

Nanoparticle inhalation augments particle-dependent systemic microvascular dysfunction

Timothy R Nurkiewicz^1,2 , Dale W Porter^2,3 , Ann F Hubbs³ , Jared L Cumpston³ , Bean T Chen³ , David G Frazer^2,3 and Vincent Castranova^2,3

¹Center for Interdisciplinary Research in Cardiovascular Sciences, West Virginia University School of Medicine, Morgantown, WV, USA

²Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, WV, USA

³Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA

author email corresponding author email

Particle and Fibre Toxicology 2008, 5:1doi:10.1186/1743-8977-5-1

Published:	12 February 2008

Abstract

Background

We have shown that pulmonary exposure to fine particulate matter (PM) impairs endothelium dependent dilation in systemic arterioles. Ultrafine PM has been suggested to be inherently more toxic by virtue of its increased surface area. The purpose of this study was to determine if ultrafine PM (or nanoparticle) inhalation produces greater microvascular dysfunction than fine PM. Rats were exposed to fine or ultrafine TiO₂ aerosols (primary particle diameters of ~1 μm and ~21 nm, respectively) at concentrations which do not alter bronchoalveolar lavage markers of pulmonary inflammation or lung damage.

Results

By histopathologic evaluation, no significant inflammatory changes were seen in the lung. However, particle-containing macrophages were frequently seen in intimate contact with the alveolar wall. The spinotrapezius muscle was prepared for in vivo microscopy 24 hours after inhalation exposures. Intraluminal infusion of the Ca²⁺ ionophore A23187 was used to evaluate endothelium-dependent arteriolar dilation. In control rats, A23187 infusion produced dose-dependent arteriolar dilations. In rats exposed to fine TiO₂, A23187 infusion elicited vasodilations that were blunted in proportion to pulmonary particle deposition. In rats exposed to ultrafine TiO₂, A23187 infusion produced arteriolar constrictions or significantly impaired vasodilator responses as compared to the responses observed in control rats or those exposed to a similar pulmonary load of fine particles.

Conclusion

These observations suggest that at equivalent pulmonary loads, as compared to fine TiO₂, ultrafine TiO₂ inhalation produces greater remote microvascular dysfunction.