Fractionation of vanadium in urine of Wistar rats as a function of time after intraperitoneal injection

[(48)V]Vanadium was intraperitoneally injected into Wistar rats. Urine and feces were collected at regular intervals (n=19) between 1 and 144 h after injection. In case of urine, maximal excretion (V activity/ml urine) of vanadium was seen 3 h after injection. In case of feces, a maximum appeared 32 h after injection. Urine samples were fractionated on two types of gel filtration column (Superose 12 HR 10/30 and Superdex Peptide 10/30). We found that vanadium in urine exists as both high (protein-bound) and low molecular mass species and that the partition about these forms depends on the time elapsed after injection. After 1 h, respectively, four (one high molecular and three low molecular mass species) and five (one high molecular and four low molecular mass species) vanadium peaks were present in the chromatograms of the Superose 12 and the Superdex Peptide columns. Then 3 h after injection, a different high molecular species showed up in the chromatograms, while the first high molecular and some low molecular mass species disappeared. Vanadium in urine after 8 h occurred as one high (slightly different from the high molecular complex after 3 h) and one low molecular mass complex. However, after 48 h the pattern changed again and vanadium in urine was excreted largely as one low molecular mass species, presumably one of the species that also occurred 1 h after injection but was not present in the period 6-24 h.