IN-VITRO AUTORADIOGRAPHIC STUDIES OF THE BIODISTRIBUTION OF RADIOPHARMACEUTICALS ON BLOOD-ELEMENTS

In the present study we evaluated the binding of the radiopharmaceutic als sodium pertechnetate (Na (TcO4)-Tc-99m), methylenediphosphonic aci d (Tc-99m-MDP) and glucoheptonate acid (Tc-99m-GHA) to blood elements using centrifugation and radioautographic techniques. Heparinized bloo d was incubated with the labelled compounds for 0, 1, 2, 3, 4, 6 and 2 4 h. Plasma (P) and blood cells (BC) were isolated and precipitated wi th 5% trichloroacetic acid (TCA), and soluble (SF) and insoluble fract ions (IF) were separated. Blood samples were prepared (0 and 24 h) and coated with LM-I radioautographic emulsions and percent radioactivity (%rad) in P and BC was determined. The binding of Na (TcO4)-Tc-99m (% rad) to P was 61.2% (0 h) and 46.0% (24 h), and radioautography showed 63.7% (0 h) and 43.3% (24 h). The binding to BC was 38.8% (0 h) and 5 4.0% (24 h), and radioautography showed 36.3% (0 h) and 56.7% (24 h). Tc-99m-MDP study presented 91.1% (0 h) to P and 87.2% (24 h), and radi oautography showed 67.9% (0 h) and 67.4% (24 h). The binding to BC was 8.9% (0 h) and 12.8% (24 h), and radioautography showed 32.1% (0 h) a nd 32.6% (24 h). Tc-99m-GHA study was 90.1% (0 h) to P and 79.9% (24 h ), and radioautography showed 67.2% (0 h) and 60.1% (24 h). The bindin g to BC was 9.9% (0 h) and 20.1% (24 h), and radioautography showed 32 .8% (0 h) and 39.9% (24 h). The comparison of the obtained results sug gests that the binding to plasma and blood cells in the two techniques used (radioautography and centrifugation) is qualitatively in accorda nce.