Pitfalls and solutions in assaying anandamide transport in cells

Nonspecific binding of anandamide to plastic exhibits many features that could bemistaken as biological processes, thereby representing an important source ofconflicting data on the uptake and release of this lipophilic substance. Herein, we propose an improved method to assay anandamide transport, by using glassslides (i.e., coverslips) as physical support to grow cells. Although the resultsobtained using plastic do not differ significantly from those obtained usingglass, the new procedure has the advantage of being faster, simpler, and moreaccurate. In fact, the lack of aspecific adsorption of anandamide to the glasssurface yields a lower background and a higher precision and accuracy indetermining transport kinetics, especially for the export process. Remarkably,the kinetic parameters of anandamide uptake obtained with the old and the newprocedures may be similar or different depending on the cell type, thusdemonstrating the complexity of the interference of plastic on the transportprocess. In addition, the novel procedure is particularly suitable forvisualization and measurement of anandamide transport in intact cells by using a biotinylated derivative in confocal fluorescence microscopy.[...]