Subcutaneous injection of fish: radionuclide release from the injection site

A technique is described for the subcutaneous injection of small fish using the goldfish (Carassius auratus L.) as a model. Using radioactive tracers, (109Cd, 125I), maximum levels occur in the plasma at 4 and 16 min, with statistical plateaus evident by 2 and 4 min, respectively. The plateau level of injected material occurring in the plasma shortly after the injection exposes the tissues to a constant dose of the injected material for the duration of the plateau. In the case of 109Cd, this period is in excess of 4h. Subcutaneous injection by this method provides low variability in delivery, rapid plasma - delivery site equilibration of the injected material, and a constant plasma level of the injected material for a significant time interval. (author)