title: Myocardial imaging with a radioiodinated norepinephrine storage analog.
abstract: Meta-iodobenzylguanidine (M-IBG), an iodinated aromatic analog of the hypotensive drug quanethidine, localizes in the heart of the rat, dog, and rhesus monkey. A comparative study of tissue distribution in the dog has been performed with five myocardiophilic agents: thallium-201, I-125 16-iodohexadecanoic acid, H-3 norepinephrine, C-14 guanethidine and I-125 M-IBG. The last two compounds give heart concentrations and heart-to-blood concentration ratios similar to those of thallium-201. Planar and tomographic images of the hearts of the dog and rhesus monkey were obtained using I-131 or I-123 labeled M-IBG. Blocking studies with reserpine suggest that a major component of myocardial retention of M-IBG is sequestration within the norephinephrine storage vesicles of the adrenergic nerves. The localization of M-IBG in other organs with rich sympathetic innervation and the relative insensitivity of myocardial uptake to a wide range of loading doses lend additional support for a neuronal mode of retention.
mesh_terms: D019797:3-Iodobenzylguanidine; D000818:Animals; D002250:Carbon Radioisotopes; D004285:Dogs; D005260:Female; D006146:Guanidines; D006321:Heart / Q000000981:diagnostic imaging*; D007457:Iodine Radioisotopes; D008253:Macaca mulatta; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D010169:Palmitic Acids; D011868:Radioisotopes; D011877:Radionuclide Imaging; D051381:Rats; D012110:Reserpine / Q000494:pharmacology; D013793:Thallium; D014018:Tissue Distribution; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D006146:Guanidines; D007457:Iodine Radioisotopes; D010169:Palmitic Acids; D011868:Radioisotopes; D014316:Tritium; D019797:3-Iodobenzylguanidine; D012110:Reserpine; D013793:Thallium; D009638:Norepinephrine