Stable and radioactive tracers in Ru biokinetic studies

The feasibility of ruthenium metabolism studies by stable tracer administration, with a methodology based on proton nuclear activation, is presented. In order to test that the amount of stable tracer administered does not perturb significantly the mechanism investigated, a series of comparative experiments with administration of both radioactive and stable tracers has been performed on animals. As the most critical pathway seems to be the intravenous injections, four male rabbits were given an intravenous injection of radioactive 106Ru. Successively, the rabbits were given either a further injection of radioactive 106Ru or injection of different quantities of natural Ru. The activity of 106Ru and the concentration of natural Ru were measured in plasma samples withdrawn at different time intervals from the injections and the results were compared. Some biokinetic parameters and tissue distribution of Ru in rabbits were determined.