LOCALIZATION OF N-(2-DIETHYLAMINOETHYL)4-IODOBENZAMIDE IN THE PIGMENTED MOUSE EYE - A MICROANALYTICAL STUDY

The I-123-N-(2-diethylaminoethyl)4-iodobenzamide (I-123-BZA) is a new radiopharmaceutical used for the scintigraphic imaging of malignant me lanomas. The mechanism for BZA uptake in melanic tissues is still unkn own. Two methods of microanalysis, secondary ion mass spectrometry and electron probe X-ray microanalysis, were used to determine tissue dis tribution and subcellular location of unlabelled BZA in the C57BL6/J1 co mouse eye. Microanalysis showed elective BZA uptake by the pigmente d structures of the eye: choroidal melanocytes and retinal pigment cel ls, where it was specifically located within melanosomes. The tropism of BZA for melanic tumours, as well as for normal pigmented tissues, c ould be explained by a high affinity for the melanin pigment.