Author/Editor		Gaberšček, Simona; Zaletel, Katja; Hojker, Sergej
Title		Fiziologija ščitnice: vloga Na+/I--simporterja in metabolizem jodida
Translated title		Thyroid physiology: the role of Na+/I--symporter and iodide metabolism
Type		članek
Source		Zdrav Vestn
Vol. and No.		Letnik 69, št. 4
Publication year		2000
Volume		str. 261-5
Language		slo
Abstract		Background. Cloning of rat and human thyroid Na+/I--symporter (transport protein for iodide) has inspired a large number of studies in the field of thyroid physiology. The results of these studies have improved our understanding of various known phenomena in thyroid gland, such as the mechanism of 1) autoregulation (plasma concentration of thyroid hormones remaines within normal range regardless of iodide supply, prevailingly by inhibition of thyroid hormones secretion in conditions of iodide excess and by increased uptake of iodide in conditions of iodide depletion); 2) the Wolff Chaikoff effect (iodide excess inhibits organification by iodinated organic compounds and decreases the synthesis of thyroid hormones; escape from the acute Wolff Chaikoff effect is caused by the decreased uptake of iodide); 3) the regulation of thyroid growth (the normal thyroid growth requires adequate supply of the gland with iodine in the form of iodide while the regulation mechanisms are preserved). Conclusions. The aim of the present article is to present novel findings in the field of thyroid physiology with a special emphasis on the role of Na+/I--symporter and iodide metabolism. The influence of iodide depletion and repletion on the function of normal thyroid gland is also discussed.
Summary		Izhodišča. Kloniranje podganjega in humanega Na+/I--Simporterja (NIS-a, transportne beljakovine za jodid) je povzročilo val raziskav na področju fiziologije ščitnice. Izsledki omogočajo boljše razumevanje mehanizmov številnih do sedaj opisanih pojavov v ščitnici, npr. mehanizme: 1. avtoregulacije (plazemska koncentracija ščitničnih hormonov je v normalnem območju ne glede na preskrbo z jodidom, predvsem zaradi inhibicije sproščanja hormonov v stanju presežka jodida in zvečanega kopičenja jodida v stanju pomanjkanja jodida); 2. Wolff-Chaikoffovega učinka (presežka jodida inhibira organifikacijo prek jodiranih organskih spojin in zmanjša sintezo ščitničnih hormonov, do bega iz Wolff-Chaikoffovega učinka pa pride zaradi zmanjšanega kopičenja jodida); 3. regulacije rasti žleze (za normalno velikost žleze je nujna ustrezna preskrba žleze z jodom v obliki jodida ob ohranjenih regulacijskih mehanizmih). Zaključki. V prispevku želimo prikazati novejša dognanja na področju fiziologije ščitnice, s poudarkom na vlogi Na+/--simporterja in metabolizma jodida. Opisujemo tudi posledice premajhnega in prevelikega vnosa na funkcijo normalne ščitnice.
Descriptors		THYROID GLAND IODIDES ION TRANSPORT SODIUM THYROID HORMONES THYROTROPIN HYPOTHALAMO-HYPOPHYSEAL SYSTEM HOMEOSTASIS