The purpose of this work was to investigate the cardiovascular toxicity of different sizes and different dosages of
silica nanoparticles in Wistar rats. The three
silica nanoparticles (30, 60, and 90 nm) and one fine
silica particles (600 nm) at three doses of 2, 5, and 10 (mg/Kg bw) were used in the present experiment. After intratracheal instillation for a total of 16 times, concentration of Si in hearts and serum was measured by inductively coupled plasma optical emission spectrometer. The hematology parameters were analyzed by an automated hematology analyzer, and the inflammatory reaction, oxidative stress, endothelial dysfunction, and the myocardial
enzymes in serum were measured by kits. Our results showed intratracheal-instilled
silica nanoparticles could pass through the alveolar-capillary barrier into systemic circulation. Concentration of Si in the heart and serum depended on the particles size and dosage. The levels of
reactive oxygen species (ROS) at 5, 10 mg/Kg bw of the three
silica nanoparticles were higher than the fine
silica particles. Blood levels of
inflammation-related
high-sensitivity C-reactive protein and
cytokines such as
interleukin-1beta (IL-1β),
interleukin-6 (IL-6), and
tumor necrosis factor-alpha were increased after exposure to three
silica nanoparticles
at 10 mg/Kg bw. Moreover, the levels of IL-1β and
IL-6 at 10 mg/Kg bw of
silica nanoparticles (30 nm) were higher than the fine
silica particles. Significant decrease in
superoxide dismutase,
glutathione peroxidase and significant increase in
malondialdehyde were observed
at 10 mg/Kg bw of the three
silica nanoparticles. A significant decrease in
nitric oxide (NO) production was induced which coincided with the reduction of
nitric oxide synthase (NOS) activity and the excessive generation of ROS in rats. The levels of
intercellular adhesion molecule-l and
vascular cell adhesion molecule-l elevated significantly after exposure to three
silica nanoparticles
at 10 mg/Kg bw, which are considered as early steps of endothelial dysfunction. We conclude that cardiovascular toxicity of
silica nanoparticles could be related to the particles size and dosage. Oxidative stress could be involved in inflammatory reaction and endothelial dysfunction, all of which could aggravate cardiovascular toxicology. In addition, endothelial NO/NOS system disorder caused by nanoparticles could be one of the mechanisms for endothelial dysfunction.