Transport of dextran sulfates to rat livers

Liver subcellular distributions of three different dextran sulfates (DSs) with average molecular weight (AMW) of 3000, 20,000, and 200,000, and sulfur content of 18%, anticoagulants and antilipemic agents, were examined in rats after intravenous administration of 50 mg/kg. About 20% of the injected radioactivity was taken up by liver 15 min-3 hr after 35S-DS administration, but the uptake of 35S-DS with AMW of 200,000 was slower than that of the other DSs. About half of the radioactivity distributed in livers was found in the cytosol fraction. The cytosol fraction/liver ratio of the radioactivity gradually decreased with the increase in the nuclear fraction/liver ratio. The specific radioactivity of the lysosomal fraction was 5--20 times as large as that of the other fractions. Unchanged forms of 35S-DSs with AMW of 3000 and 20,000 were found in the lysosomal and the cytosol fractions. Administration of DSs with AMW of 20,000 and 200,000 significantly enhanced the Na+-K+-dependent ATPase activity of lysosomal fraction which has been considered to be an index of endocytosis. These findings suggest that DSs are probably transferred into liver cells by transmembrane and endocytotic transports.