Localization of low molecular weight 99mTc-labeled dimercaptodicarboxylic acids in kidney tissue.

Kidney localization of low molecular weight 99mTc-dimercaptodicarboxylic acid complexes was examined in mice. The complexes 99mTc-dimercaptosuccinic acid, 99mTc-dimercaptoglutaric acid, and 99mmTc-dimercaptoadipic acid were formed by reducing sodium 99mTc-pertechnetate with stannous chloride in the presence of 2-10 fold excess ligand at pH 2.5 or 7.5. Kidney specificity decreased as chain length between the mercapto groups increased. Optimum kidney retention occurred with complexes formed at pH 2.5. Complexes prepared at pH 7.5 were rapidly excreted through the urine and feces. Kidney localization of complexes prepared at one pH was not altered if the pH was later changed.