Stunning of iodide transport by (131)I irradiation in cultured thyroid epithelial cells.
The existence of thyroid stunning (i.e., inhibited thyroidal iodide uptake after administration of diagnostic amounts of (131)I) is controversial and is currently a subject of debate. To our knowledge, the stunning phenomenon has not been investigated previously in vitro.


METHODS
Growth-arrested porcine thyroid cells that formed a tight and polarized monolayer in a bicameral chamber were irradiated with 3-80 Gy (131)I present in the surrounding culture medium for 48 h. The iodide transport capacity after irradiation was evaluated 3 d later by measuring the transepithelial (basal to apical) flux of trace amounts of (125)I.


RESULTS
The basal-to-apical (125)I transport decreased with increasing absorbed dose acquired from (131)I; a nearly 50% reduction was observed already at 3 Gy. Stable iodide at the same molarity as (131)I (10(-8) mol/L) had no effect on the (125)I transport. Cell number and epithelial integrity were not affected by irradiation.


CONCLUSIONS
Stunning of iodide transport is detected after (131)I irradiation of cultured thyroid cells. The degree of inhibition of transport is dependent on the absorbed dose.
Postgård
Per
P
Department of Radiation Physics, Sahlgrenska University Hospital, Göteborgs Universitet, Göteborg, Sweden. per.postgård@radfys.gu.se
Himmelman
Jakob
J
Lindencrona
Ulrika
U
Bhogal
Nirmal
N
Wiberg
Dennis
D
Berg
Gertrud
G
Jansson
Svante
S
Nyström
Ernst
E
Forssell-Aronsson
Eva
E
Nilsson
Mikael
M
D000818:Animals; D001692:Biological Transport; D002478:Cells, Cultured; D007454:Iodides / Q000493:pharmacokinetics*; D007457:Iodine Radioisotopes; D011829:Radiation Dosage; D013552:Swine; D013961:Thyroid Gland / Q000166:cytology / Q000528:radiation effects*
D007454:Iodides; D007457:Iodine Radioisotopes