Effects of Silica on Mitochondrial Functions of the Proximal Tubule Cells in Rats

Abstract

Aim: Despite the belief that silica (Si) is an inert and non-toxic ingredient, latest studies indicated that it is a potent mitochondria activator and Si-induced ROS generation is involved in the inflammatory reactions of silicotic lungs. Si cytotoxicity has been well studied in phagocytic cells, but its effects on the mitochondria of proximal tubule cells which are continuously exposed to filtered blood-borne soluble Si were not known. Methods: Using renal cortical slices and isolated mitochondria, the effect of high dietary Si on the mitochondrial functions of proximal tubule cells was studied in rats exposed to 50 mg/kg sodium metasilicate-containing water for 8 days. Results: Digested Si did not accumulate in kidney cortex, it was totally eliminated in the urine. Glomerular filtration rate as well as urine output were normal. Despite unaltered blood and cortex Si levels, ammonia production of cortical slices and isolated mitochondria was increased significantly and this was further increased by L-NAME pre-treatment. Elevated mitochondrial oxygen utilization was associated with increased ammonia production. Cyclosporin-A-sensitive mtPTP increase was associated with unchanged K_ATP channels in the mitochondria of Si-exposed rats. Conclusion: These results suggested that dietary Si increases both extracellular and intracellular ammoniagenesis by elevating mitochondrial oxygen utilisation.

Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds: New perspectives for therapy

“…Dietary silicon in the form of sodium metasilicate activates formation of ammonia by elevating mitochondrial oxygen utilisation as shown in a controlled animal experiment [91]. These findings further corroborate the hypothesis that sodium silicate might be responsible for immunostimulatory effects of Barodon®.…”

“…Pure sodium metasilicate (Na 2 SiO 3 ) also bears immunostimulatory effects and acts as a potent mitochondria activator [91]. Dietary silicon in the form of sodium metasilicate activates formation of ammonia by elevating mitochondrial oxygen utilisation as shown in a controlled animal experiment [91].…”

Nanocomposite Ti/hydrocarbon plasma polymer films from reactive magnetron sputtering as growth support for osteoblast‐like and endothelial cells

“…20,21 For example, these materials can induce the formation of reactive oxygen species, resulting in damage to the cell membrane and mitochondrial metabolism, as well as inflammatory reactions. 20,21 Therefore, for cell experiments, the films were deposited on standard cell culture substrates such as polystyrene dishes or microscopic glass slides. The latter was used for studies of cell number, spreading, and immunofluorescence staining of selected cell adhesion-mediating molecules and cell-specific markers of differentiation.…”

Interaction of vulcanization and reinforcement of CB on dynamic property of NR characterized by RPA2000

“…The silicon‐containing substrates used for the deposition of films in order to characterize their physicochemical properties can have a cytotoxic effect and can prevent the growth of various cell types 20, 21. For example, these materials can induce the formation of reactive oxygen species, resulting in damage to the cell membrane and mitochondrial metabolism, as well as inflammatory reactions 20, 21. Therefore, for cell experiments, the films were deposited on standard cell culture substrates such as polystyrene dishes or microscopic glass slides.…”