LOCALIZATION OF RADIOLABELED ENZYME-INHIBITORS IN ADRENAL-GLAND

  • 1 January 1976
    • journal article
    • research article
    • Vol. 17  (11) , 998-1002
Abstract
Tissue distribution studies were performed in rats and dogs at 5 time intervals between 10 min-24 h after i.v. injection of 1 of the following radiolabeled adrenocortical enzyme inhibitors: 3H-aminoglutethimide. 125I-3-iodoaminoglutethimide, 3H-SKF-12185, 125I-3-SKF-12185, 3H-metyrapone, 3H-metyrapol, 3H-amphenone B, and 3H-SU-10603. In rats, 3H-SKF-12185 showed the highest uptake in the whole adrenal (3.5% kg dose/g at 1 h). In dogs 3H-metyrapol showed the highest uptake in the adrenal cortex (9% kg dose/g at 1 h), and the peak cortex-to-liver concentration ratio was 57 at 2 h. These peak uptakes were comparable to those obtained with the conventional iodocholesterols, but they were reached much earlier, with elimination of most of the adrenal radioactivity by 24 h. These properties would permit the use of 123I as the label and a higher tracer dose, resulting in a higher photon flux. The radiolabeled enzyme inhibitors show promise as adrenal-scanning agents, with a markedly shortened scanning procedure, a lower absorbed radiation dose and better resolution.

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