Transport of the organic cations gonyautoxin 2/3 epimers, a paralytic shellfish poison toxin, through the human and rat intestinal epitheliums

Abstract

The aim of this work is to study the mechanisms involved in gonyautoxins (GTXs) intestinal absorption. For this purpose, we studied the transport of GTX 2/3 epimers by intestinal epithelial cell lines (IEC-6 and Caco-2) cultured on polycarbonate filters. Specific transport was calculated by subtracting from the flux of GTX 2/3 measured at 37°C that occurring at 4°C, this being an indication of transcellular transport. The transcellular apical-to-basolateral (A-B) flux in Caco-2 cell monolayers, was greater than that in the opposite direction, suggesting the involvement of an active transport system favoring the absorption of the toxin. However, in IEC-6 cells the transcellular basolateral-to-apical (B-A) specific transport of the toxin was greater than that in the opposite direction. The A-B and B-A fluxes were, respectively, 127±26 and 205±23nmol/min, suggesting the presence of a prevalent secretive process of the toxin in IEC-6 cells. The A-B transport of GTX 2/3 epimers in Caco-2 ce