DISTRIBUTION AND CHEMICAL FORM OF SELENIUM IN MICE AFTER ADMINISTRATION OF SELENOCYSTINE

To elucidate the relationship between chemical forms of selenium in ti ssues and subacute liver damage induced by selenocystine (T. Hasegawa et al., Arch. Toxicol., 68, 91 (1991)), the distribution and chemical form of selenium were investigated in ICR male mice treated with the c hemical orally (50 mg/kg) and intravenously (5 mg/kg). The time-distri bution of selenium in plasma, erythrocytes and liver after separate ad ministration varied. However, Sephadex G-150 chromatograms of plasma, and stroma-free hemolysate from mice treated orally or intravenously w ith selenocystine, revealed that selenium exists mainly in the albumin and hemoglobin fractions, respectively, and is neither route- or time -dependent. Sephadex G-150 chromatograms of liver cytosol of the anima ls 1 h after oral administration or 1 and 6 h after intravenous admini stration showed two selenium-containing fractions, void volume and a l ow-molecular fraction (K-av = 0.85); 6 h after oral treatment, however , animals had an additional high-molecular fraction (K-av = 0.45). Lev els of acid-volatile selenium and dialyzable seleniun in the fraction with a K-av value of 0.45 were similar, being 31.2% and 30.3%, respect ively. No acid-volatile selenium was recognized in the non-dialyzable high-molecular fraction. The present study demonstrated that when sele nocystine is administered orally to mice, the selenium which produces acid-volatile selenium by acidification mag bind to protein sulfhydryl groups in the liver cytosol; this was not seen in the case of intrave nous administration.