Biochemical studies of the renal radiopharmaceutical compound dimercaptosuccinate. I. Subcellular localization of 99mTc-DMS complex in the rat kidney in vivo.

Subcellular distribution of 99mTc-DMS (dimercaptosuccinic acid) complex in the rat kidney has been studied. One hour after IV injection of labelled DMS preparation kidney tissue homogenate was subjected to differential subfractionation to obtain cell organelles. Radioactivity distribution in relation to total radioactivity of kidney homogenate obtained in five repeated experiments was as follows (+/- SD): nuclei 4.56% (+/- 0.7); mitochondria 5.97% (+/- 0.7); microsomes 3.63% (+/- 0.8) and cytosol 30.92% (+/- 1.8). Specific activities expressed as counts/min/mg of protein were 148,520 (+/- 15%), 97,440 (+/- 17.7%) and 76,180 (+/- 29%) for mitochondria, cytosol and microsomes respectively. Specific activity of the nuclei was 230.060 (+/- 27%) counts/min/mg of DNA. These results show without doubt that this renal imaging agent, successfully used in human medicine, penetrates into kidney cells where it binds mostly to soluble cytoplasmic proteins and mitochondria and to a lesser extent, to both microsomes and nuclei.