Long-term effect of norepinephrine on iodide uptake in FRTL-5 cells.
The sympathetic nervous system plays a role in the regulation of thyroid function. In FRTL-5 rat thyroid cells, norepinephrine (NE) acutely depresses intracellular I- by increasing I- efflux. The present study was undertaken to determine the effect of NE on iodide transport after a longer time period. NE inhibited the ability of thyrotropin (TSH) to induce iodide uptake by FRTL-5 cells after 48 or 72 hours, but not after 24 hours. The effect of NE was more evident with increasing concentrations of TSH. NE did not modify the rate of I- efflux. Inhibition was associated with a decrease in the Vmax and no change in the Km for iodide influx. To determine if this was a generalized effect of NE on thyroid cell membrane, the uptake of alpha-aminoisobutyric acid (a nonmetabolizable aminoacid) and of 2-deoxyglucose was measured. NE did not inhibit TSH stimulation of the uptake of the two compounds. NE inhibited the action of dibutyryl cAMP (dbcAMP) on iodide uptake in a similar manner to TSH, but did not alter the cyclic adenosine monophosphate (cAMP) levels increased by TSH. The effects of different adrenoreceptor agonists and antagonists demonstrated that norepinephrine acts through an alpha1-adrenergic receptor.
Juvenal
G J
GJ
Argentine Atomic Energy Commission, and Human Biochemistry Department, School of Medicine, University of Buenos Aires, Argentina.
Pregliasco
L B
LB
Krawiec
L
L
Bocanera
L V
LV
Silberschmidt
D
D
Pisarev
M A
MA
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D003847:Deoxyglucose / Q000378:metabolism; D007454:Iodides / Q000037:antagonists & inhibitors*; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013972:Thyrotropin / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000621:Aminoisobutyric Acids; D007454:Iodides; D018340:Receptors, Adrenergic, alpha-1; C100049:2-aminoisobutyric acid; D013972:Thyrotropin; D003847:Deoxyglucose; D000242:Cyclic AMP; D009638:Norepinephrine