Thyroid hormone actions and membrane fluidity Blocking action thyroxine on triiodothyronine effect

Mendoza, Diego de; Moreno, Hortensia; Massa, Eddy M.; Morero, Roberto D.; Farı́as, Ricardo N.

doi:10.1016/0014-5793(77)81089-2

Cited by 32 publications

(8 citation statements)

References 33 publications

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“…Thyroxine analogs bound to plasma membranes may affect membrane fluidity (De Mendoza et al, 1977), the activity of Na+,K +-ATPase (Edelman and Ismail-Beigi, 1974) or adenylate cyclase (Segal and Ignbar, 1982). However, the structurefunction relationship of these activities is not available and the correlation with quantum chemical indices was not examined.…”

Section: Discussionmentioning

confidence: 99%

Molecular orbital studies of the action of thyroid hormone analogs: Effects on oxygen consumption of mitochondria and horseradish peroxidase-catalyzed NADH oxidation

Sakurada

Aida²,

Nagata³

et al. 1988

J Biol Phys

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ABSTRACT:The electronic structure of thyroxine and related compounds were calculated by semiempirical molecular orbital methods. When the quantum chemical indices obtained were compared with the structure-activity relationship obtained so far by in vivo and h7 vitro assays, it was found that HOMO (highest occupied molecular orbital) energy levels of thyroxine and its analogs are well correlated with the increase in oxygen consumption of rat kidney mitochondria determined by in vitro assay. This finding permits the hypothesis that these compounds may play a role in activating the electron transport system of mitochondria by mediating the oxidation-reduction of cytochromes. Furthermore, HOMO energy levels of thyroxine and phenol derivatives were found to correlate well with the stimulation of horseradish peroxidase-catalyzed oxidation of NADtt. This suggests that the step of electron removal from these compounds by the enzyme system may be a rate-limiting step, confirming the view that phenoxy-radicals meditate the whole reaction.

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Section: Discussionmentioning

confidence: 99%

Molecular orbital studies of the action of thyroid hormone analogs: Effects on oxygen consumption of mitochondria and horseradish peroxidase-catalyzed NADH oxidation

Sakurada

Aida²,

Nagata³

et al. 1988

J Biol Phys

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“…Such a rise in [Ca2+], would be opposed by the plasma membrane Ca2+-ATPase; this enzyme is rapidly activated by T3 and could contribute to the transiency of the rise in [Ca2+]1 ). It is interesting to note that the stimulation of this enzyme by nanomolar concentrations of T3 is modified when the fatty acid composition of the membrane is altered (de Mendoza, Moreno, Massa & Farias, 1977), suggesting that this lipid soluble hormone may interact directly with the phospholipid bilayer.…”

Section: Discussionmentioning

confidence: 98%

Tri-Iodothyronine Increases Intra-Cellular Calcium Levels in Single Rat Myocytes

Lomax

Cobbold²,

Allshire³

et al. 1991

Journal of Molecular Endocrinology

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We have studied the effects of acute administration of triiodothyronine (T3) on cytosolic free calcium levels [Ca2+]i in single rat myocytes microinjected with aequorin. Ventricular myocytes were isolated by perfusing rat hearts with collagenase, and healthy, rod-shaped cells were injected to less than 1% of their volume with aequorin. The photons emitted from single cells were measured and a conversion to [Ca2+]i made on the basis of an in vitro calibration after the remaining aequorin had been discharged by cell lysis. Only cells that depolarized reversibly (showing elevated [Ca2+]i levels) when superfused with 80 mM KCl, and which gave a substantial signal on lysis with distilled water were used. The [Ca2+]i rose from a resting value of 150 +/- 56 nM (mean +/- SD, n = 14) by 127 +/- 47 nM on depolarization with 80 mM KCl. Application of T3 (1-100 nM) led to an increase (P less than 0.05) in [Ca2+]i (mean amplitude of 152 +/- 35 nM) before returning to baseline. The median duration of these events was 10 min (range = 1.4-34.4 min). The time to response was shorter when 100 nM T3 was applied (median and range; 6.8, 0-14 min) than when 1 nM T3 was used (16, 7.0-56.1 min) (P less than 0.05). To conclude, physiological concentrations of thyroid hormones caused rapid but transient stimulation of [Ca2+]i in single rat myocytes.

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“…Thriiodothyronine 1 Oe9 M also decreases the value of h of acetylcholinesterase from rats fed a corn oil supplemented diet [ 8,9] : however, glucagon did not block the thriiodothyronine effect (not shown). In addition, glucagon did not affect the epinephrineinduced changes on the values of h of the enzyme from rats fed a lard supplemented diet (row 15).…”

Section: Resultsmentioning

confidence: 99%

Membrane cooperative enzymes: interplay of insulin, glucagon and epinephrine on rat erythrocyte acetylcholinesterase system

et al. 1978

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Thyroid hormone actions and membrane fluidity Blocking action thyroxine on triiodothyronine effect

Cited by 32 publications

References 33 publications

Molecular orbital studies of the action of thyroid hormone analogs: Effects on oxygen consumption of mitochondria and horseradish peroxidase-catalyzed NADH oxidation

Molecular orbital studies of the action of thyroid hormone analogs: Effects on oxygen consumption of mitochondria and horseradish peroxidase-catalyzed NADH oxidation

Tri-Iodothyronine Increases Intra-Cellular Calcium Levels in Single Rat Myocytes

Membrane cooperative enzymes: interplay of insulin, glucagon and epinephrine on rat erythrocyte acetylcholinesterase system

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