Detection of angiotensin II type 1 receptor ligands by a cell-based assay.

This work describes a cell-based assay that does not depend on radioactivity or laboratory animals for the detection of ligands of angiotensin II type 1 receptor (AT1R). The assay makes use of stable transfected Chinese hamster ovary cells (CHO-AT1R) expressing the AT1R. A sequential saturation assay principle was used in which receptor binding sites of the CHO-AT1R cells are blocked by the analyte in a concentration-dependent manner. Afterwards, TAMRA-angiotensin II, a fluorescence-labeled ligand, was added to bind to the remaining free binding sites of the receptor. In consequence, the fluorescence signal determined is inversely proportional to the concentration of the analyte.