Fate of 125I-labeled Compounds in Rats after Intravenous Injection (I): Metabolic Fate of Sodium-125I-iodide
1993 Volume 8 Issue 4 Pages 457-469
Details
1993 Volume 8 Issue 4 Pages 457-469
After the pretreatment with the potassium iodine containing drinking water, so called iodine-block, the absorption, distribuion, and excretion of radioactivity in rats were observed compared with those in the non-treated (control) rats after intravenous injection of 125I-NaI. Consequently, the differences are found as follows ;
1) The change of the radioactivity level in plasma of the iodineblock rats was slightly different from that of the control through 8hr after the injection. From 8hr to 24hr, the plasma levels were remarkably different ; rapid decline was observed in the case of iodine-block rats. Since 24hr, a similar half life was found in each condition, though the curve of the iodine-block was about 1/15 of the control.
2) A few % of the total radioactivity in plasma was found in the acid insoluble fraction through an early period after the injection. After that, the ratio in the acid insoluble fraction increased with time elapsed, and its ratio reached about 40% in the case of the iodine-block, and about 70% for the control.
When the plasma samples 5min and 2hr after the injection were subjected to electrophoresis, the radioactive fraction was found to be present in the albumin fraction.
3) The 125I-NaI was recovered mainly in urine. The cumulative excretion percent of the dose for 72hr was about 98% for the iodine-block rats, though it was about 74% for the control. The remaining fractions were retained mostly in the body, but a slight fecal excreti on was also observed.
4) Biliary excretion of the radioactivity within 48hr after the injection was 34% and 27% for the iodine-block and the control, respectively.
5) The autoradiographic data 5min after the injection indicated a saturated photo density over the stomach contents, kidney and urinary bladder. And a relatively higher density over the skeletal muscle was observed in the case of the iodine-block rat than the control rat. Fourty eight hours after the injection, saturated density over the thyroid in control rats was present, but the iodine-block rat did not show any density over the whole body section.
The radioactive proteins of the thyroid were separated by the electrophoresis. The results indicated that remarkable radioactivity was associated with a thyroglobulin spot.
