99mTc-Glutathione: Role of Reducing Agent on Renal Retention

The biodistribution of 99mTc-labeled glutathione in mice was dependent on the presence of Sn2+. The radioactivity ratio of the kidney to the liver increased from 1.17 to >6.0 as the Sn2+ ion concentration in the glutathione injection solution increased from 0 to 1.11 mM. The activity in the kidneys increased for the 1st 2 h and then decreased for 4 h. In the absence of the Sn2+, the radioactivity in the liver, kidney, and blood decreased 30 min after administration. Apparently, the reducing agent Sn2+ increases the retention of glutathione in the kidney.