Compartment analysis of metabolism of chromium(III) in rats of various ages.

The metabolism of chromium(III) was studied in groups of female Wistar rats of various ages (35, 60, and 120 days) after a single intravenous injection of 51CrCl3 in trace amounts. In all the animals, the plasma disappearance curve could be adequately described by a sum of three exponential terms between 0 and 265 h postinjection. A three-compartment mammillary model is proposed that permits the description of Cr(III) metabolism in quantitative terms. The model defines compartment volumes, clearances by exchange, and clearances by excretion. The total excretory clearance is the sum of three components: urinary clearance (fu), fecal clearance (fd), and a residual clearance (fs), corresponding to an apparently irreversible deposition of chromium into long term body reservoirs. The parameters of the model are reported for each age group; when their values are expressed per 100 g of body wt, all the components of the excretory clearance decrease with age. In all cases elimination takes place primarily via the urine and fs accounts for 31-41% of the total excretory clearance. Consistent with the model, 51Cr was found to accumulate with time in several organs such as bone, kidney, spleen, and liver after a single intravenous injection of 51CrCl3.