Biochemical studies of the renal radiopharmaceutical compound dimercaptosuccinate. III. Subcellular distribution and interaction of 99Tc-DMS complex with macromolecules in rat kidney homogenates in vitro.

Rat kidney tissue homogenates, incubated in vitro with 99Tc-DMS were subjected to differential centrifugation. Specific radioactivities of subcellular fractions were as follows: cytosol 13,552, microsomes 3,600, mitochondria, 2,707 cpm/mg protein, and nuclei, 2,642 cpm/mg DNA. The cytosol fraction was further analyzed by ion-exchange chromatography on DEAE-Sephadex A-25 column. In this way it was separated into several distinct protein zones, three of them bearing a significant amount of 99Tc-DMS preparation. The highest specific radioactivities of proteins were eluted from the DEAE-Sephadex column with 30 mmol/l and 50-110 mmol/l NaCl solution. Total nucleic acids isolated from purified nuclei, mitochondria and microsomes contained a certain amount of bound 99Tc-DMS complex. Nuclear nucleic acids had the highest specific radioactivity, suggesting that 99Tc-DMS complex penetrates into the nuclei.