Effects of Multi-Walled Carbon Nanotubes in the Lungs and Aortas of ApoE-Deficient Mice Fed a Normal Diet

Multi-walled carbon nanotubes (MWCNT) possess unique physic-chemical properties for a diverse utilization. However, potential toxic effects also have been raised. To test whether pulmonary exposure of MWCNT induces toxicity in pulmonary and cardiovascular system, apolipoprotein E-deficient (apoE-/-) mice fed a regular diet were exposed to MWCNT (40 mu g, once each week for 16 consecutive weeks) by pharyngeal aspiration. Mice were sacrificed on 1 and 7 d following the last exposure. Bronchoalveolar lavage (BAL) fluid, BAL cells, urine, aortas and plasma were obtained to evaluate pulmonary toxicity, oxidative stress and atherosclerotic lesion formation. Cell-free BAL fluid measurements showed significantly elevated levels of total protein, lactate dehydrogenase, surfactant protein-D, and mucin in MWCNT-exposed mice at 1 and 7 d post-exposure, compared to control. Total BAL cells and polymorphonuclear leukocytes counts were markedly increased in MWCNT-exposed mice at both time points. However, aortic atherosclerotic lesions, total plasma cholesterol levels and urinary 8-hydroxy-2'-deoxyguanosine were not significantly altered by MWCNT exposure. Results indicate that sub-chronic lung exposure of MWCNT exerts toxicity in mouse lungs without apparent atherogenic effects.