RECEPTOR-BINDING RADIOTRACERS FOR THE ANGIOTENSIN-II RECEPTOR - RADIOIODINATED [SAR(1),ILE(8)]ANGIOTENSIN-II

The potential for imaging the angiotensin II receptor was evaluated using the radioiodinated peptide antagonist [I-125][Sar(1),Ile(8)]angiotensin II. The radioligand provides a receptor-mediated signal in several tissues in rat (kidneys, adrenal and liver). The receptor-mediated signal of 3% ID/g kidney cortex should be sufficient to permit imaging, at least via SPECT. The radiotracer is sensitive to reductions in receptor concentration and can be used to define in viva dose-occupancy curves of angiotensin II receptor ligands. Receptor-mediated images of [I-123][Sar(1),Ile(8)]angiotensin II were obtained in the rat kidney and Rhesus monkey liver.