TC-99M-INSULIN - LABELING, BIODISTRIBUTION AND SCINTIIMAGING IN ANIMALS

Porcine insulin was labeled with Tc-99m by direct tin reduction. More than 95% labeling efficiency was obtained on paper chromatography in s aline and methyl ethyl ketone. The stability of the labeled compound w as confirmed by paper chromatography at 3 h post-labeling and by human serum albumin (HSA) challenge. PAGE pattern indicated no change in th e electrophoretic behavior and the molecular size of insulin after the labeling procedure. Biodistribution in rats shows that kidney took up the maximum amount of Tc-99m-insulin; maxima being maintained through out 24 h post-injection. Liver and intestine were the other organs wit h significant uptake; the rest localizing little or negligible radioac tivity. Most of the radioactivity was excreted via the renal pathway i nto urine. Scintiimages conformed to the biodistribution data. The res ults of this study present the potential of Tc-99m-labeling of insulin by a simple method.