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Thyroid hormone action on mitochondria. IV. Redox states of intrinsic pyridine nucleotides in hypothyroidism, and influence of L-thyroxine.
Journal of Bioenergetics and Biomembranes ( IF 3 ) Pub Date : 1976-10-01 , DOI: 10.1007/bf00761448
F L Hoch 1
Affiliation  

Measurements of fluorescence at >420 nm and extracted NADPH in mitochondria obtained from the livers of hypothyroid rats show that the addition of Pi, ADP and glutamate rapidly reduces over 90% of the total reducible intrinsic pyridine nucleotides in State 3, compared with 20% in normals. The total fluorescence intensity change and reducible NADP+ is about twice normal in hypothyroid mitochondria. Adding 6-30 microM L-thyroxine to hypothyroid mitochondria in vitro decreases and delays the substrate-induced reduction of pyridine nucleotides, and excludes both NADP+ from such reduction and NADPH from oxidation by added ADP + Pi, without changing the high NADP(H) content. The correcting actions of the hormone are rapidly reversed by albumin, probably by binding free hormone. Changes in respiration do not appear to account for these observations. There is indirect evidence for decreased phosphorylation of added ADP in hypothyroid mitochondria, and a correction by added hormone. The hormonal actions on NADP(H) redox reactions are not reproduced by 1 to 6 microM dinitrophenol in vitro. L-Thyroxine appears to specifically block the participation of NADP(H) in redox reactions in mitochondria from hypothyroid rats, perhaps by effecting a sequestration of the nucleotide, by inhibiting the pyridine nucleotide transhydrogenase, or by activating an energy-linked process that competes with transhydrogenation.

中文翻译:

甲状腺激素对线粒体的作用。四、甲状腺功能减退症中固有吡啶核苷酸的氧化还原状态,以及 L-甲状腺素的影响。

对从甲状腺功能减退大鼠肝脏获得的线粒体中 >420 nm 的荧光和提取的 NADPH 的测量表明,添加 Pi、ADP 和谷氨酸迅速减少了 90% 以上的状态 3 中的总可还原的内在吡啶核苷酸,而在法线。甲状腺功能减退线粒体中的总荧光强度变化和可还原的 NADP+ 大约是正常值的两倍。在体外向甲状腺功能减退线粒体中添加 6-30 microM L-甲状腺素可减少并延迟底物诱导的吡啶核苷酸还原,并通过添加的 ADP + Pi 将 NADP+ 和 NADPH 从这种还原中排除,同时将 NADPH 排除在氧化中,而不会改变高 NADP(H)内容。白蛋白可能通过结合游离激素迅速逆转激素的纠正作用。呼吸的变化似乎不能解释这些观察结果。有间接证据表明甲状腺机能减退线粒体中添加的 ADP 磷酸化降低,并通过添加激素进行校正。体外 1 到 6 microM 二硝基苯酚不能再现对 NADP(H) 氧化还原反应的激素作用。L-甲状腺素似乎特异性地阻止 NADP(H) 参与甲状腺功能减退大鼠线粒体氧化还原反应,可能是通过影响核苷酸的螯合、抑制吡啶核苷酸转氢酶或通过激活与氢化。
更新日期:2019-11-01
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