Distribution of iodine into blood components of the Sprague-Dawley rat differs with the chemical form administered.
It has been reported previously that radioactivity derived from iodine distributes differently in the Sprague-Dawley rat depending on the chemical form administered (Thrall and Bull, 1990). In the present communication we report the differential distribution of radioactivity derived from iodine (I2) and iodide (I-) into blood components. Twice as much radioiodine is in the form of I- in the plasma of animals treated with 125I- compared to 125I2-treated rats. No I2 could be detected in the plasma. With an increase in dose, increasing amounts of radioactivity derived from 125I2-treated animals distribute to whole blood compared to equivalent doses of 125I-, reaching a maxima at a dose of 15.8 mumol I/kg body weight. Most of the radioactivity derived from I2 associates with serum proteins and lipids, in particular with albumin and cholesteryl iodide. These data indicate a differential distribution of radioactivity depending on whether it is administered as iodide or iodine. This is inconsistent with the commonly held view that iodine (I2) is reduced to iodide (I-) before it is absorbed systemically from the gastrointestinal tract.
Thrall
K D
KD
Pharmacology/Toxicology Graduate Program, College of Pharmacy, Washington State University, Pullman.
Bull
R J
RJ
Sauer
R L
RL
D000818:Animals; D000838:Anions / Q000097:blood / Q000493:pharmacokinetics; D001773:Blood Cells / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D007455:Iodine / Q000097:blood* / Q000737:chemistry; D007457:Iodine Radioisotopes; D008055:Lipids / Q000097:blood; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
D000838:Anions; D007457:Iodine Radioisotopes; D008055:Lipids; D007455:Iodine