Vasomotor dysfunction in human subcutaneous arteries exposed ex vivo to food-grade titanium dioxide

Animal studies have shown that titanium dioxide (TiO₂) exposure affects arterial vasomotor function, whereas little is known about the effects in arteries from humans. This study investigated vasomotor responses after direct exposure of human subcutaneous arteries to food-grade TiO₂ (E171) (14 or 140 μg/ml) for 30 min and 18 h. Vasomotor responses to bradykinin, 5-hydroxytryptamine (5-HT), sarafotoxin 6c (S6c) and nitroglycerin were recorded in wire-myographs. Vasoconstrictor responses to 5-HT were increased in arteries exposed to E171 for 18 h (P < 0.05). Furthermore, an increase in S6c responses was seen in low concentration E171 exposed arteries (30 min exposure; P < 0.05). The vasorelaxation response to nitroglycerin was increased in low concentration E171 exposed arteries (30 min exposure; P < 0.05). Vasorelaxation responses to bradykinin were unaffected after treatment with E171. There was no difference in gene expression levels of intercellular cell adhesion molecule 1, vascular cell adhesion molecule 1, 5-hydroxytryptamine receptor 1B, 5-hydroxytryptamine receptor 2A, endothelin receptor A and endothelin receptor B in E171 exposed arteries after exposure to TiO₂ for 30 min or 18 h. In conclusion, this study shows that the same type of vasomotor dysfunction is found in artery segments of rats and humans following ex vivo exposure to E171.