1996 Volume 11 Issue 6 Pages 599-606
The feto-placental transfer of 125I-E6010 and the excretion into milk were studied in pregnant and lactating rats after a single intravenous administration of 0.4 mg/kg of 125I-E6010.
1. At 15 min after a single intravenous administration of 125I-E6010 to rats on day 13 and 19 of gestation, the radioactivity level in the fetus was 245 ?? 348 times lower than that present in maternal plasma, but most of that was not TCA-precipitable. At later time on day 19 of gestation, the level of radioactivity in the fetal thyroid tissue was higher than that in the other fetal and maternal tissues, however, it was suggested that radioactivity in the thyroid results from the accumulation of free 125I. These results suggested that 125I-E6010 administered to pregnant rats was not transfered into the fetus as an intact E6010.
2. After a single intravenous administration of 125I-E6010 to lactating rats, the TCA-precipitable radioactivity was found in the milk, and its level increased and reached maximum at 24 hr, but the immunoreactive E6010 was not detected at any time. Then, most of the radioactivity in the milk was considered to be an endogeneous high molecular weight compounds into which a free iodine, produced by degradation of 125I-E6010, was incorporated.
