Nuclear imaging uses of radio-labelled atrial natriuretic factor

In a method of diagnosing and monitoring diseases characterized by the binding of a ligand to a receptor, the improvement comprising:

• administering to a live subject a radiolabeled reagent selected from the group consisting of radiolabeled atrial natriuretic factor and radiolabeled active fragments and analogues thereof, and imaging the target organ area of the live subject and determining the amount of radiation emitted by the radiolabelled reagent then present in the target organ area, which level is affected by an increase or decrease in atrial natriuretic factor receptor density or affinity in said target organ which is characteristic of said disease.

A method of diagnosing abnormal uptake, binding and/or displacement of atrial natriuretic factor in an organ of a live mammalian subject which method comprises administering a diagnostically effective amount of radio-labelled atrial natriuretic factor, active fragment or analog thereof to said live subject and subsequently imaging the live subject or organ with a suitable radio-detecting device, quantifying the uptake, binding and/or displacement of said radio-labelled atrial natriuretic factor, active fragment or analog thereof in said organ, and comparing the uptake, binding and/or displacement of atrial natriuretic factor, active fragment or analog with the uptake, binding and/or displacement of radio-labelled atrial natriuretic factor, active fragment or analog in a reference organ in said live subject or in another live subject of the same mammal species.