Thyroxine and Na+ transport in toad: role in transition from poikilo- to homeothermy

Détails

ID Serval
serval:BIB_91A87BD14850
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Thyroxine and Na+ transport in toad: role in transition from poikilo- to homeothermy
Périodique
American Journal of Physiology
Auteur(s)
Rossier  B. C., Rossier  M., Lo  C. S.
ISSN
0363-6143
Statut éditorial
Publié
Date de publication
03/1979
Volume
236
Numéro
3
Pages
C117-24
Notes
Journal Article --- Old month value: Mar
Résumé
The effects of thyroxine (T4) on Na+ transport, oxygen consumption (QO2), and Na+-K+-ATPase activity were studied in the urinary bladder and liver of the toad Bufo marinus. In the bladder, T4 in vitro (10(-8) to 10(-6) M) had no significant effect on these parameters during 15 h of incubation. When injected intraperitoneally (approximately 20 microgram/(kg body wt.day) for 6 days), T4 lowered base-line, short-circuit current by 62% (P less than 0.0025) and potential difference by 37% (P less than 0.001), increasing tissue resistance by 40% (P less than 0.02). T4 depressed QO2/DNA (-25%, P less than 0.05) with no significant effect on Na+-K+-ATPase activity. In liver, T4 increased the recovery per cell DNA of mitochondrial proteins by 32% (P less than 0.025), corresponding to an increased QO2 (stage IV) of isolated mitochondria per cell DNA (+54%, P less than 0.01). There was no significant effect on Na+-K+-ATPase activity. These results suggest that, unlike its function in the rat, T4 in the toad does not regulate cellular thermogenesis by inducing Na+-K+-ATPase. This major difference could account at least in part for the transition from poikilothermy to homeothermy. In addition, T4 has a distinct inhibitory effect on Na+ transport in the urinary bladder, which suggests an antagonism to the action of aldosterone.
Mots-clé
Animals *Body Temperature Regulation Bufo marinus/physiology Evolution Female Liver/metabolism Male Oxygen Consumption/*drug effects Sodium/*metabolism Sodium-Potassium-Exchanging ATPase/*metabolism Thyroxine/*pharmacology Urinary Bladder/metabolism
Pubmed
Web of science
Création de la notice
24/01/2008 14:01
Dernière modification de la notice
03/03/2018 19:29
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