Cellular Uptake Assay
Cell-based uptake assays can be used to measure either the transport or internalization of labeled compounds into cells or the potency of unlabled test compounds in inhibiting this transport. Labeled substances can be neurotransmitters, metabolites, drugs or proteins. Applications include:
- Determination of IC50 values for test compounds against cellular uptake of radiolabeled neurotransmitters.
- Determination of IC50 values for test compounds against uptake of tritium or 14C-labeled metabolites or drugs.
- Cellular uptake and internalization of 125I-labeled proteins.
Radiometric release assays can be used to quantify the efflux of labeled substances from cells. Efflux can be via membrane ion channels, membrane transport or from cell lysis. Applications include:
- 86Rb+ rubidium efflux assay for quantification of drug effects on stimulation or inhibition of ligand-gated ion channel activity (nicotinic).
- Efflux or release of 3H and 125I-labeled drugs or proteins from cells.
- 51Cr chromium release assay for quantification of cell-mediated cytotoxicity.
Inhibition of [3H]dopamine uptake into rat brain synaptosomes by the dopamine transport inhibitors, GBR 12909 and cocaine (left panel), shown in comparison with inhibition of [3H]mazindol binding (right panel).
Stimulation of 86Rb+ efflux from SH-SY5Y cells by the nicotinic receptor agonists, epibatidine and nicotine
Loss of 125I-labeled trastuzimab from SKBr3 cells, following addition of a saturating concentration of unlabelled antibody to the medium