Abstract

Introduction: Vitamin E is conceived as a mixture of isomers of tocopherols, being -tocopherol the most known. There are others isomers present at food with less known attributes; therefore we have evaluated side by side, the acute impact of ,  and  on living Caco-2 cells. Methods: Living cell imaging was accomplished by epifluorescent microscopy technique in an open chamber modality. Cytosolic Ca2+ recording was achieved by tracking of Fura-2, a ratiometric calcium indicator. Antioxidant cellular impact was followed by monitoring intracellular H2O2 levels with HyPer biosensor. In this study we also determined fluctuations in intracellular Na+ and pH by SBFI and BCECF, respectively. Results: Tocopherol isomers evoked cytosolic Ca2+ increases at 5 M with different kinetics and magnitude in Caco-2 cells. Removal of extracellular Ca2+ exposed that  and  isomers mobilize calcium only from intracellular stores, whereas -tocopherol has an extracellular component in its calcium response. At low concentrations, only -tocopherol was able to evoke a significant deflection in the biosensor signal. Further experiments are directed to unveil the role of Ca2+ response as a mechanism connected to increase the antioxidant cytosolic machinery. Conclusions: Tocopherol isomers evoked distinct Calcium response in Caco-2 cells. Despite at high concentration all isomers increased cytosolic Ca2+, only the response evoked by -tocopherol exposure was sensitive to removal of extracellular Ca2+. By silencing the Ca2+ responses with calcium quelators or inducing Ca2+ increases with other agents (ionomycin i.e.) we postulate a mechanistic connection between cytosolic Ca2+ fluctuations with rapid antioxidant activity changes.