Excitation-inhibition of stomach smooth muscles by the nano-sized titanium dioxide materials

Abstract

The aim of our work consisted in the investigation of the effects of TiO₂ nanoparticles (average size of 21 ± 5 nm) on the contractile activity of circular smooth muscles from rat's stomach. The cumulative increase in the concentration of TiO₂ (10⁻⁶–10⁻³ mg/ml) is accompanied by a dose-dependent inhibition of spontaneous contractions. When using TiO₂ concentrations 10⁻³, 2.5·10⁻², and 5·10⁻² mg/ml, the significant increase, of acetylcholine- and K⁺-induced contractions are observed. The activation of acetylcholine-induced contractions is essentially inhibited by D-600. Vice versa, the atropine presence didn't eliminate the TiO₂-stimulated activation of high- K⁺-induced contractions. Nanoparticles didn't affect the contractions caused by the release of Ca²⁺ from sarcoplasmic reticulum, but their effects are essentially eliminated via the previous inhibition of the mitochondria function by sodium azide.