Uptake of titanium from TiO₂nanoparticle exposure in the isolated perfused intestine of rainbow trout: nystatin, vanadate and novel CO₂-sensitive components

Nanoparticle (NP) uptake across the gut is poorly understood. In vitro gut sac preparations and isolated perfused intestines were used to investigate the absorption mechanism(s). Exposure of whole gut sacs to 1 mg/l TiO₂ NPs for 4 h caused total Ti metal concentrations to increase in the intestine, with 80% or more of the Ti in the mucosa. Perfused intestines showed a saturable time-dependent accumulation of total Ti, which increased when the CO₂ in the gas mixture was lowered to 0.5%. Adding cyanide did not stop Ti uptake, and 100 µmol/l vanadate (ATPase inhibitor) caused a 2.8-fold reduction in the net uptake rate of Ti for TiO₂ NP exposure. Luminal additions of nystatin (endocytosis inhibitor), blocked the uptake of Ti from both bulk and TiO₂ NP treatments. The data demonstrate Ti uptake across the intestine from TiO₂ NP exposures, involving CO₂-dependent and nystatin-sensitive mechanisms.