Steady-State Oxidation of Glucose in Hyperthyroid and Hypothyroid Rats

Dow, Dorothy S.; Allen, C. E.

doi:10.1139/o61-098

Cited by 18 publications

(8 citation statements)

References 21 publications

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“…Earlier work in this laboratory, based on steady state oxidation of glucose in both the hjrperthyroid and hypothyroid rat, suggested that the effect of thyroxine is exerted on total oxidative activity and not specifically on glucose oxidation (1). Recent work in another laboratory, based on the overall character of the thyroxine-induced increase in mitochondria1 activities, also favors the idea that the action of thyroxine is more a question of alteration in the number of respiratory phosphorylating assemblies rather than a single rate-limiting enzyme (2).…”

Section: Introductionmentioning

confidence: 91%

Influences of Thyroxine and Insulin on the Turnover and Fate of High-Energy Phosphate

Dow¹

1964

Can. J. Biochem.

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Ingestion by the weanling rat of thyroxine in a n amount greatly in excess of physiological requirements resulted in significant increases in the rates of turnover of the high-energy compounds phosphocreatine (PC), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) and in significant decreases in their concentrations in skeletal muscle. Nucleoside phosphorylase and myokinase activities and rates of pyrophosphate splitting of ATP and of utilization of ATE' for nuclear syntheses were unaltered in thyrotoxic muscle. The lindings suggest that increased extramitochondrial utilization of A'TP for glycolysis may be the factor responsible for the increased phosphorylating capacity of the thyrotoxic animal. An effect of thyroxine on mitochondrial permeability as well as on rate of formation of the high-energy intermediate would appear to explain the observed results.A further enhancement of the already markedly elevated thyrotoxic rate of phosphorylation was effected by the superimposition of insulin. Insulin also effected increases in the concentrations of the high-energy compounds. I t is apparent that insulin acts by reducing the utilization of ATP for phosphorylation of glucose and thus increases the ~liitocho~ldrial availability of high-energy acceptor. This increased mitocholldrial affinity for high-energy compounds results in a n enhancement of mitochondrial energy transfer processes.The findings appear t o i~ivolve both thyroxine and insuliu in the control of cell structure.

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Section: Introductionmentioning

confidence: 91%

Influences of Thyroxine and Insulin on the Turnover and Fate of High-Energy Phosphate

Dow¹

1964

Can. J. Biochem.

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“…Dow and Allen [146] found that the total oxida-tion of glucose by the glycolytic pathway is increased in hyperthyroid rats, whereas the hexose monophosphate shunt is completely inhibited. Redding and Johnson [496] studied the erythrocytes of patients with thyrotoxicosis and also found increased glycolysis and inhibition of the hexose monophosphate shunt.…”

Section: Metabolismmentioning

confidence: 99%

Physiological Effects of the Thyroid Hormones

et al. 1975

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The thyroid gland has a powerful influence over the activities of the whole body. If the function of the gland is for any reason lost, serious disturbances of chemical and morphological structure arise and are manifested as physical and mental disorders. The diversity of the action of thyroid hormones on physiological functions, on the metabolic rate, and on the activity of various enzyme systems both in the body as a whole and in tissue preparations has been known for a long time. Our knowledge of the role of thyroid hormones is based on experiments in which a particular thyroid hormone has been given to healthy and athyrotic animals and on extensive clinical observations on patients with hyperthyroid and hypothyroid states.The effect of thyroid hormones in vivo is expressed as reactions of whole organs and of individual physiological functions and morphological structures. The internal secretions of the thyroid gland modify growth and metamorphosis, the utilization of oxygen by the body as a whole or by tissue preparations in vitro, various aspects of metabolism, and the activity of particular enzyme systems.The extreme diversity of the effects observed after injection of thyroid hormone may reflect the primary action of this agent on a single link fundamental to the mechanism of biochemical processes in the cell or on a single morphological structure responsible for the proper integration of processes at the cell level. These problems will be examined fully later. Here I shall merely state that when the action of a thyroid hormone is discussed, the term is used not only with respect to the thyroxine and triiodothyronine produced in the thyroid gland, but also to several of their derivatives and analogs. However, we know that all compounds with the biological activity 125 Y. K. Turakulov et al., Thyroid Hormones

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“…Oxidation of hexoses was accelerated by administered thyroid hormone, either through equal increases in both the phosphogluconate and the glycolytic pathways, or mainly through increased glycolysis; the route chosen may depend upon the degree of hyperthyroidism, low doses of hormone accelerating glycolysis mainly (Glock, McLean & White head, 1956) and depressing the phosphogluconate path (Dow & Allen, 1961). Hypothyroidism depressed glucose exidation via both paths (Dow & Allen, 1961). The mechanisms of the thyroid hormonal effects on glycolysis may be via one or more routes.…”

Section: Lipid Metabolismmentioning

confidence: 99%

“…And the activity of two enzymes of the glycolytic pathway, enolase and lactic dehydrogenase, were increased in the livers of thyrotoxic rats (Bargoni et al, 1961), but they are probably not rate-controlling steps; the activities of a number of the glycolytic enzymes were decreased in hypothyroidism (Bargoni et al, 1964). Lastly, the hormonal control of the generation of NADH and NADPH by mitochondria might also affect both glycolysis and the phosphogluconate pathway (Dow & Allen, 1961). Increased glucose uptake or oxidation, or both, have been observed in the muscles and in the livers of hyperthyroid animals, and also in cultures of animal cells, sperm, Saccharomyces cerevisiae, or Acetobacter aerogenes treated with thyroid hormones.…”

Section: Lipid Metabolismmentioning

confidence: 99%

Biochemistry of hyperthyroidism and hypothyroidism

Hoch

1968

Postgraduate Medical Journal

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SummaryThe thyroid hormones act directly on mitochondria, and thereby control the transformation of the energy derived from oxidations into a form utilizable by the cell. Through their direct actions on mitochondria, the hormones also control indirectly the rate of protein synthesis and thereby the amount of oxidative apparatus in the cell. A rationale for the effects of thyroid hormone excess or deficiency is based upon studies of the mechanism of thyroid hormone action. In hypothyroidism, slow fuel consumption leads to a low output of utilizable energy. In hyperthyroidism, rapid fuel consumption leads to a high energy output, but as efficiency decreases, the utilizable energy produced decreases. Many of the chemical and physical features of these diseases can be reduced to changes in available energy.

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Steady-State Oxidation of Glucose in Hyperthyroid and Hypothyroid Rats

Cited by 18 publications

References 21 publications

Influences of Thyroxine and Insulin on the Turnover and Fate of High-Energy Phosphate

Influences of Thyroxine and Insulin on the Turnover and Fate of High-Energy Phosphate

Physiological Effects of the Thyroid Hormones

Biochemistry of hyperthyroidism and hypothyroidism

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