Studies on absorption, distribution, metabolism and excretion of orally administered 35S-dextran sulfate in rats and dogs, (1)

The 35S-radioactivities in plasma after oral administration of 35S-dextran sulfate (35S-DS) remained at high levels for 4 hrs. in both rats and dogs. The 35S-radioactivity excreted in urine was found to be 2 - 3% of the dose within 24 - 96 hours, irrespective of species and sex. Fecal excretion of the radioactivity in dogs was 90 - 93% of the dose within 96 hrs. After oral administration of 35S-DS to rats, the radioactivity was concentrated in the liver and kidney in addition to the intestinal tissue. Smaller amounts of radioactivity were also found in other tissues such as the heart, lung, spleen and cerebrum. The radioactivity in the liver and kidney was higher, and declined more slowly, than in plasma. When compared to Tomizawa's data obtained in rats (1971), the ratios of the absorbed radioactivity to dose were approximately equal, as judged from the urinary excretion data, but absorption appeared to be more rapid and the levels of plasma radioactivity seemed to be better sustained. (Evans, J.)