Katyare S S, Bangur C S, Howland J L
Department of Biochemistry, Faculty of Science, M.S. University of Baroda, India.
Biochem J. 1994 Sep 15;302 ( Pt 3)(Pt 3):857-60. doi: 10.1042/bj3020857.
The effects of in vivo treatment with graded doses (0.5-1.5 micrograms/g body weight) of thyroid hormones, tri-iodothyronine (T3) and thyroxine (T4), for 4 consecutive days to euthyroid rats on the respiratory activity of isolated brain mitochondria were examined. T4 stimulated coupled State-3 respiration with glutamate, pyruvate + malate, ascorbate + tetramethyl-p-phenylenediamine and succinate, in a dose-dependent manner; T3 was effective only at the highest (1.5 micrograms) dose employed. T4 was more effective than T3 in stimulating respiratory activity. State-4 respiratory rates were in general not influenced except in the case of the ascorbate + tetramethyl-p-phenylenediamine system. Primary dehydrogenase activities, i.e. glutamate dehydrogenase, malate dehydrogenase and succinate dehydrogenase, were stimulated about 2-fold; interestingly mitochondrial but not cytosolic malate dehydrogenase activity was influenced under these conditions. The hormone treatments did not greatly influence the mitochondrial cytochrome content. The results therefore suggest that thyroid hormone treatment not only stimulates primary dehydrogenase activities but may also directly influence the process of mitochondrial electron transfer.
研究了连续4天给正常甲状腺功能的大鼠体内注射不同剂量（0.5 - 1.5微克/克体重）的甲状腺激素三碘甲状腺原氨酸（T3）和甲状腺素（T4），对分离的脑线粒体呼吸活性的影响。T4以剂量依赖性方式刺激了与谷氨酸、丙酮酸+苹果酸、抗坏血酸+四甲基对苯二胺和琥珀酸相关的耦联状态3呼吸；T3仅在所用的最高剂量（1.5微克）时有效。在刺激呼吸活性方面，T4比T3更有效。除了抗坏血酸+四甲基对苯二胺系统外，状态4呼吸速率一般不受影响。初级脱氢酶活性，即谷氨酸脱氢酶、苹果酸脱氢酶和琥珀酸脱氢酶，被刺激了约2倍；有趣的是，在这些条件下，线粒体苹果酸脱氢酶活性受到影响，而胞质苹果酸脱氢酶活性未受影响。激素处理对线粒体细胞色素含量影响不大。因此，结果表明甲状腺激素处理不仅刺激初级脱氢酶活性，还可能直接影响线粒体电子传递过程。
