Gallium-67 ( 67 Ga) has been used as a tumor or inflammation-imaging agent in nuclear medicine. We recently reported that the peak of serum alanine aminotransferase (ALT) level was 1 d after carbon tetrachloride (CCl 4 ) treatment in rats. However, the peak of Ga by the hepatocytes is carried out during liver regeneration rather than during hepatic disorder by CCl 4 treatment. 67 Ga); carbon tetrachloride (CCl 4 ); liver tissue; hepatocyte; lipid peroxidation; bromodeoxyuridine (BrdU) (w/v) trichloroacetic acid, 0.375% (w/v) thiobarbituric acid dissolved in 0.25 M of hydrochloric acid], the mixture was heated for 15 min in a boiling water bath. After cooling, the precipitate was removed by centrifugation at 2000ϫg for 10 min. Following decanting of the supernatant, the absorbance was determined at 535 nm against a blank that contained all the reagents minus sample. The MDA concentration from the samples was calculated using an extinction coefficient of 1.56ϫ10 Key words. The results were expressed as the concentration of MDA/mg protein.Flow Cytometric Analysis of Cell Cycle Cell cycle was analyzed using a BrdU Flow Kit (Becton Dickinson, San Diego, CA, U.S.A.). BrdU was dissolved in phosphate buffered saline (PBS) and was given intravenously (10 mg/kg) 2 h before killing. Incorporation of BrdU into hepatocytes was detected by FACScan (Becton Dickinson). RESULTS Changes in the Lipid Peroxidation of Hepatocytes from CCl 4 -Treated MiceTo ascertain the degree of disorder in the hepatocytes, we determined the lipid peroxidation by thiobarbituric acid assay (Fig. 1). The peroxidation increased after CCl 4 treatment and showed the highest value (7.2 times higher than that of normal mice) 1 d after the treatment.Changes in Serum ALT Level after CCl 4 Treatment Serum ALT level also increased after CCl 4 treatment and reached a maximum in 1 d (Fig. 2). Two days after the treatment the value rapidly decreased. (Fig. 3), while the uptake of 67 Ga by the hepatocytes showed the highest value (8.5 times higher than that of normal mice) 2 d after treatment (Fig. 4). Changes in the Incorporation of Bromodeoxyuridine into Hepatocytes after CCl 4 TreatmentTo confirm DNA synthesis of hepatocytes during liver regeneration after CCl 4 -induced hepatic disorder, we determined their incorporation of BrdU (Fig. 5). Incorporation reached a maximum 2 d after CCl 4 treatment. DISCUSSIONWe recently reported that serum ALT level of CCl 4 -treated rat reached a maximum 1 d after the treatment, whereas the uptake of 67 Ga by the liver tissue and hepatocytes was highest 2 d after treatment. 9)In the present study, we confirmed the precise index of disordered hepatocytes by the degree of lipid peroxidation (Fig. 1). The lipid peroxidation of hepatocytes from CCl 4 -treated mice was greatly increased within 1 d of the treatment. Furthermore, serum ALT (a conventional indicator of hepatic disorder) was also increased within 1 d (Fig. 2). This result was consistent with that of CCl 4 -treated rats, 9) and indicated that hepatocyte destruc...