Thyroid calorigenesis in isolated, perfused rat liver: minor role of active sodium‐potassium transport.

Folke, M.; Sestoft, L

doi:10.1113/jphysiol.1977.sp011909

Cited by 62 publications

(17 citation statements)

References 21 publications

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“…It is notable that the turnover of some groups of cyclic reactions that expend relatively large amounts of ATP (involved in the maintenance of ionic and substrate homeostasis), e.g., Na + /K + transporters in the plasma membrane, is largely inducible by thyroid hormone [76,77]. This is particularly relevant in skeletal muscle, a large tissue in which a small change in the rate of energy expenditure can impact substantially on the total body thermogenesis.…”

Section: Thyroid Hormone-dependent Thermogenic Mechanisms In Skeletalmentioning

confidence: 98%

Adaptive Activation of Thyroid Hormone and Energy Expenditure

et al. 2005

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The mechanisms by which thyroid hormone accelerates energy expenditure are poorly understood. In the brown adipose tissue (BAT), activation of thyroid hormone by type 2 iodothyronine deiodinase (D2) has been known to play a role in adaptive energy expenditure during cold exposure in human newborns and other small mammals. Although BAT is not present in significant amounts in normal adult humans, recent studies have found substantial amounts of D2 in skeletal muscle, a metabolically relevant tissue in humans. This article reviews current biological knowledge about D2 and adaptive T3 production and their roles in energy expenditure.

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Section: Thyroid Hormone-dependent Thermogenic Mechanisms In Skeletalmentioning

confidence: 98%

Adaptive Activation of Thyroid Hormone and Energy Expenditure

et al. 2005

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“…In another intact tissue, the perfused liver, no significant metabolic cost of Na pumping could be detected (Folke & Sestoft, 1977), using oxygen uptake as an index of the over-all metabolic rate, and ouabain as a specific inhibitor of the process. On the other hand, it remains that the effects of thyroid hormones on skeletal muscle are a stimulation of active Na-K transport (Asano, 1978;present study), an increase in the number of ouabain binding sites (Lin & Akera, 1978; present study) and a somewhat selective increase in the maximum Na-K ATPase activity (Asano et al 1976).…”

Section: Discussionmentioning

confidence: 99%

Thyroid hormones and the energetics of active sodium‐potassium transport in mammalian skeletal muscles.

Biron¹,

Burger²,

Chinet³

et al. 1979

The Journal of Physiology

105

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SUMMARY1. The steady-state heat production rate (1) of soleus muscles obtained from adult mice in various thyroid states was measured in a perfused microcalorimeter. The ouabain-suppressible fractions of E and 42K influx were compared and the energetic efficiency of active Na-K transport assessed.2. Hypothyroidism with plasma thyroxine concentrations below 1 jug/100 ml. was induced by pretreatment with 131I or perchlorate. In soleus muscles isolated from treated animals, mean E9 values were 2541 + 0 7 and 24-2 + 0 5 mcal.g wet wt.-'. min-for the 1311 and the perchlorate series respectively, i.e. about 30 % lower than the control level (36.3 + 1t5 mcal.g wetwt.-l.min-1). Followingtriiodothyronine treatment, X was increased by about 45 %.3. In muscles from hypothyroid (1311 and perchlorate series), euthyroid and hyperthyroid mice ouabain (10-3 M) induced a rapid decrease in ER of 1-6 + 0.1 and 1-4 + 0*1 2-5 + 0-2, and 4-3 + 0-6 mcal.g wet wt.-'.min-' respectively, i.e. between 6 and 8 % of1E.4. In muscles obtained from hypothyroid, euthyroid and hyperthyroid mice, the ouabain-suppressible component of 42K influx was 0-17 + 0 04, 031 + 0-02 and 0-45 + 0-02 Itmole. g wet wt.-. min-respectively. Whereas the total number of ouabain binding sites varied appreciably with the thyroid status, the Na-K contents of soleus or diaphragm muscles showed no significant changes.5. Notwithstanding the parallelism between the changes in basal X and ouabainsensitive components of E and K influx with the thyroid status, it is concluded that active Na-K transport cannot be considered a primary effector of thyroid thermogenesis in intact mammalian skeletal muscle. The direct contribution of active Na-K transport to this thermogenesis was indeed small compared with the over-all cellular energy dissipation.6. The minimum over-all energetic efficiency of the transport process in the intact muscle (30-35 %) was not dependent on the thyroid status.

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“…Assim, qualquer reação que resulte em hidrólise de ATP também promove a termogênese, por dois mecanismos: calor liberado como resultado direto da hidrólise do ATP; e indiretamente, calor liberado durante a regeneração da molécula de ATP, devido à ineficiência termodinâmica mitocondrial. (17,18).…”

Section: Hidrólise De Atpunclassified

Hormônios tireóideos, UCPs e termogênese

Bianco

2000

Arq Bras Endocrinol Metab

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RESUMOCalor é um subproduto da transformação de energia, em suas diversas formas, durante a síntese e a utilização do ATP. Nos animais homeotér-micos, o calor derivado das funções biológicas -estando o organismo em repouso e à temperatura ambiente -é utilizado para manter o organismo próximo a 37°C. Essa termogênese obrigatória está associada à ineficiência termodinâmica intrínseca mitocondrial, derivada da presença de proteínas desacopladoras (UCPs, uncoupling proteins). Durante a exposição ao frio, o organismo é capaz de gerar mais calor através da termogênese facultativa, por processos que também envolvem UCPs. Os hormônios tireóideos influenciam diretamente a expressão da UCP-1 e, indiretamente, a expressão das UCP-2 e UCP-3. ABSTRACTHeat is a byproduct of the energy transformation in its various forms during the synthesis and utilization of ATP. In homeothermic animals the heat derived from the biological functions -at rest and at room temperature -is used to keep the body temperature close to 37°C. This obligatory thermogenesis is associated to the intrinsic mitochondrial thermodynamic inefficiency caused by the presence of uncoupling proteins (UCPs). During cold exposure the body is capable of generating more heat by means of the facultative thermogenesis, a series of processes that also involves the function of UCPs. The thyroid hormones influence directly the expression of UCP-1 and indirectly the expression of UCP-2 and UCP-3. Furthermore, they also accelerate the turnover of several cyclical biochemical reactions and pathways that lead to greater ATP breakdown and energy expenditure. Keywords: Thyroid hormones; Thermogenesis; UCP; ATP C ALOR É UM SUBPRODUTO DA TRANSFORMAÇÃO da energia em seus vários estados (1). Por exemplo, a energia química contida na gasolina é liberada de forma explosiva durante sua oxidação, sendo transformada no motor do automóvel em energia mecânica (trabalho) que movimenta o veículo. O calor resultante da transformação de energia química em energia mecânica aquece o motor. A maioria (~75%) da energia derivada da oxidação da gasolina é perdida na forma de calor. Ao contrário, num motor elétrico, mais de 90% da energia é transformada em trabalho, o que faz com que este tipo de motor esquente menos e seja mais econômico e eficiente do ponto de vista termodinâmico.

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Thyroid calorigenesis in isolated, perfused rat liver: minor role of active sodium‐potassium transport.

Cited by 62 publications

References 21 publications

Adaptive Activation of Thyroid Hormone and Energy Expenditure

Adaptive Activation of Thyroid Hormone and Energy Expenditure

Thyroid hormones and the energetics of active sodium‐potassium transport in mammalian skeletal muscles.

Hormônios tireóideos, UCPs e termogênese

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