Gregory R B, Berry M N
Department of Medical Biochemistry, School of Medicine, Flinders University of South Australia, Adelaide.
Biochim Biophys Acta. 1991 Dec 3;1098(1):61-7.
The respiratory capacities of hepatocytes, derived from hypothyroid, euthyroid and hyperthyroid rats, have been compared by measuring rates of oxygen uptake and by titrating components of the respiratory chain with specific inhibitors. Thyroid hormone increased the maximal rate of substrate-stimulated respiration and also increased the degree of ionophore-stimulated oxygen uptake. In titration experiments, similar concentrations of oligomycin or antimycin were required for maximal inhibition of respiration regardless of thyroid state, suggesting that the changes in respiratory capacity were not the result of variation in the amounts of ATP synthase or cytochrome b. However, less rotenone was required for maximal inhibition of respiration in the hypothyroid state than in cells from euthyroid or hyperthyroid rats, implying that hepatocytes from hypothyroid animals contain less NADH dehydrogenase. The concentration of carboxyatractyloside necessary for maximal inhibition of respiration was 100 microM in hepatocytes from hypothyroid rats, but 200 microM and 300 microM in hepatocytes from euthyroid and hyperthyroid rats, respectively, indicating a possible correlation between levels of thyroid hormone and the amount or activity of adenine nucleotide translocase. The increased capacity for coupled respiration in response to thyroid hormone is not associated with an increase in the components of the electron transport chain or ATP synthase, but correlates with an increased activity of adenine nucleotide translocase.
通过测量氧气摄取速率以及用特定抑制剂滴定呼吸链的成分，对源自甲状腺功能减退、甲状腺功能正常和甲状腺功能亢进大鼠的肝细胞的呼吸能力进行了比较。甲状腺激素增加了底物刺激呼吸的最大速率，也增加了离子载体刺激的氧气摄取程度。在滴定实验中，无论甲状腺状态如何，都需要相似浓度的寡霉素或抗霉素来最大程度地抑制呼吸，这表明呼吸能力的变化不是ATP合酶或细胞色素b数量变化的结果。然而，与甲状腺功能正常或甲状腺功能亢进大鼠的细胞相比，甲状腺功能减退状态下最大程度抑制呼吸所需的鱼藤酮较少，这意味着甲状腺功能减退动物的肝细胞中NADH脱氢酶较少。甲状腺功能减退大鼠肝细胞中最大程度抑制呼吸所需的羧基苍术苷浓度为100微摩尔，而甲状腺功能正常和甲状腺功能亢进大鼠肝细胞中的浓度分别为200微摩尔和300微摩尔，这表明甲状腺激素水平与腺嘌呤核苷酸转位酶的数量或活性之间可能存在相关性。甲状腺激素引起的偶联呼吸能力增加与电子传递链或ATP合酶的成分增加无关，但与腺嘌呤核苷酸转位酶活性增加相关。
