KINETICS OF CD2-INJECTION OF CD-METALLOTHIONEIN-II( IN PLASMA, LIVER AND KIDNEYS AFTER SINGLE INTRAVENOUS)

To explore the kinetics of Cd2+ in the body, rats received a single in travenous injection of CdCl2 or Cd-saturated metallothionein-II at 0.3 mg Cd/kg body weight. Cd2+ in the two agents was biexponentially elim inated from plasma: rapidly in the first 5 min, and gradually later. C ompared with CdCl2, Cd-saturated metallothionein-II showed lower Cd2concentrations in plasma during the first 30 min; larger values for pa rameters concerning distribution of Cd2+, its total body clearance and half-life time in the P phase. Cd2+ uptake in the liver was higher wi th CdCl2, and, conversely, in the kidneys it was higher with Cd-satura ted metallothionein-II. In Cd-saturated metallothionein-II, the renal content of Cd2+ reached a maximum (8 mu g Cd2+/g tissue) on day 1, gra dually decreasing thereafter; there was a higher area under the Cd2+ c ontent-time curve, and a lower mean residence time of Cd2+; th, kidney s showed severe necrosis and defluxion of proximal tubular cells at da ys 1 and 5, although there were regenerative and reversion signs on da y 5. These findings suggested that, in the case of Cd-saturated metall othionein-II, Cd2+ being taken into the cells of proximal tubules was excluded predominantly due to cellular death and the resultant defluxi on.