Vanadium metabolism in sheep. III. Influence of dietary vanadium on kinetics of 48V administered orally or intravenously and comparison of compartmental and graphical models.

Radiotracer techniques were used to investigate the influence of dietary stable V on the excretion, distribution and blood clearance kinetics of 48V in 14 rams averaging 58 kg body weight. Rams were fed a basal diet with added levels of 0, 50 or 200 mg/kg V as NH4 VO3 for 25 wk before either oral or iv administration of the isotope. A three-compartment model was determined by graphical logarithmic analysis of blood disappearance data from iv-dosed rams and compared with a simultaneous multicompartment model, which made it possible to ascribe physiological processes to the components of the graphical model. The principal route of excretion of 48V administered iv was via urine, whereas the isotope given orally was excreted almost entirely by way of feces, resulting in low tissue and urinary 48V levels. Increasing dietary V increased (P less than .05) the percentage of dose excreted in urine regardless of dosing route, but dietary V had no effect on 48V excreted in feces. Stable dietary V had no effect on blood clearance rates of orally or iv-dosed rams. Dietary V addition decreased 48V concentration in kidney (P less than .01), liver, spleen, testes and muscle (P less than .05) of iv-dosed rams, but had no effect in rams dosed orally. Kidney, bone, liver and spleen retained the highest levels of 48V activity 144 h after dosing. Dietary V appeared to have a minimal effect on V kinetics in rams.