Hafner R P, Nobes C D, McGown A D, Brand M D
Department of Biochemistry, University of Cambridge, England.
Eur J Biochem. 1988 Dec 15;178(2):511-8. doi: 10.1111/j.1432-1033.1988.tb14477.x.
We have determined the relationship between rate of respiration and protonmotive force in oligomycin-inhibited liver mitochondria isolated from euthyroid, hypothyroid and hyperthyroid rats. Respiration rate was titrated with the respiratory-chain inhibitor malonate. At any given respiration rate mitochondria isolated from hypothyroid rats had a protonmotive force greater than mitochondria isolated from euthyroid controls, and mitochondria isolated from hyperthyroid rats had a protonmotive force less than mitochondria isolated from euthyroid controls. In the absence of malonate mitochondrial respiration rate increased in the order hypothyroid less than euthyroid less than hyperthyroid, while protonmotive force increased in the order hyperthyroid less than euthyroid less than hypothyroid. These findings are consistent with a thyroid-hormone-induced increase in the proton conductance of the inner mitochondrial membrane or a decrease in the H+/O ratio of the respiratory chain at any given protonmotive force. Thus the altered proton conductance or H+/O ratio of mitochondria isolated from rats of different thyroid hormone status controls the respiration rate required to balance the backflow of protons across the inner mitochondrial membrane. We discuss the possible relevance of these findings to the control of state 3 and state 4 respiration by thyroid hormone.
我们已经确定了从甲状腺功能正常、甲状腺功能减退和甲状腺功能亢进的大鼠中分离出的经寡霉素抑制的肝线粒体中呼吸速率与质子动力之间的关系。用呼吸链抑制剂丙二酸滴定呼吸速率。在任何给定的呼吸速率下，从甲状腺功能减退的大鼠中分离出的线粒体的质子动力大于从甲状腺功能正常的对照大鼠中分离出的线粒体，而从甲状腺功能亢进的大鼠中分离出的线粒体的质子动力小于从甲状腺功能正常的对照大鼠中分离出的线粒体。在没有丙二酸的情况下，线粒体呼吸速率按甲状腺功能减退＜甲状腺功能正常＜甲状腺功能亢进的顺序增加，而质子动力按甲状腺功能亢进＜甲状腺功能正常＜甲状腺功能减退的顺序增加。这些发现与甲状腺激素诱导线粒体内膜质子电导率增加或在任何给定质子动力下呼吸链的H⁺/O比值降低是一致的。因此，从不同甲状腺激素状态的大鼠中分离出的线粒体的质子电导率或H⁺/O比值的改变控制了平衡线粒体内膜质子回流所需的呼吸速率。我们讨论了这些发现与甲状腺激素对状态3和状态4呼吸的控制的可能相关性。
