The effects of glutathione depletion on the biodistribution of Cu(PTSM) in rats

The tissue retention of radiocopper afforded by intravenous injection of the proposed blood flow imaging agent, ⁶²Cu-labeled copper(II) pyruvaldehyde bis(N⁴-methylthiosemicarbazone) [Cu(PTSM)], is thought to result from reductive decomposition of the copper(II) complex by intracellular sulfhydryls (e.g. glutathione, GSH). To determine if the tissue uptake and retention of this tracer adequately measures perfusion in tissues containing altered GSH concentrations, the biodistribution of copper-67 labeled Cu(PTSM) was determined in GSH-depleted rats. Despite treatment to induce relatively large reductions in tissue GSH levels, it was found that only very small changes in the biodistribution of copper-labeled Cu(PTSM) occurred in the treated rats compared to untreated controls.