Two radioiodinated probes, 125I-cholesteryl oleate (125I-CO), a derivative of a natural constituent of lipoproteins, and 1-(2-chlorophenyl)-1-(4 [125I] iodophenyl)-2, 2- dichloroethane (125I-DDD), an analog of the adrenolytic drug o, p′-DDD (mitotane), were