Pathways of Cr (III) and Cr (VI) in the rat after intratracheal administration

51Cr-labelled Cr3+ and CrO2-4 solutions were administered intratracheally to male rats in doses of 0.1 and 10 μg of Cr per rat to evidentiate metabolic differences especially in the lung and in the mechanisms of excretion. Twenty four hours after administration the highest 51 Cr amount was present in the lungs for both valency states, being in the Cr (III)-treated group, however, about two times higher. In all other tissues tested the values in the Cr (VI)-treated animals were much higher.Intracellularly, in the Cr (III)-treated group more than 40% of the total lung homogenate was found in the nuclear fraction and only 10% in the cytosol. In the Cr (VI)-treated group 25% was present in the nuclei and more than 50% in the cytosol. Gel filtration 24 h after intratracheal injection showed that in both cytosols chromium was eluted in three peaks including a low-molecular-weight component. Quantitatively, however, the ratios between the 51Cr associated with the three peaks were significantly different between ...