LIVER MITOCHONDRIAL PYROPHOSPHATE CONCENTRATION IS INCREASED BY CA-2+ AND REGULATES THE INTRAMITOCHONDRIAL VOLUME AND ADENINE-NUCLEOTIDE CONTENT
LIVER MITOCHONDRIAL PYROPHOSPHATE CONCENTRATION IS INCREASED BY CA-2+ AND REGULATES THE INTRAMITOCHONDRIAL VOLUME AND ADENINE-NUCLEOTIDE CONTENT
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DOI：
10.1042/bj2460715
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发表时间：
1987-09-15
影响因子：
4.1
通讯作者：
HALESTRAP, AP
中科院分区：
文献类型：
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作者：
DAVIDSON, AM;HALESTRAP, AP
1. 在 ATP、Mg2+、Pi 和呼吸底物存在下孵育的离体供能大鼠肝线粒体的基质焦磷酸盐 (PPi) 含量约为 100 pmol/mg 蛋白质。 2. 与亚微摩尔 [Ca2+] 一起孵育后，该值增加了 300%。 Ca2+ 对 PPi 的影响与先前报道的基质体积增加之间存在相关性 [Halestrap、Quinlan、Whipps 和 Armston (1986) Biochem。 J.236, 779-787]。在 0.3 μM-Ca2+ 时观察到半最大效应。 3.与这些作用同时发生的是，总腺嘌呤核苷酸含量以羧基苍术苷敏感的方式增加。 4.用0.2-0.5 mM丁酸盐孵育对线粒体肿胀、基质PPi和总腺嘌呤核苷酸含量产生相似但较小的影响。在 Ca2+ 之后添加丁酸盐（反之亦然）会导致 Ca2+ 诱导的线粒体肿胀停止或逆转，而基质 PPi 增加 30 倍。 5. 添加白术苷或在培养中省略 ATP 大大增强了 Ca2+ 诱导的膨胀，而不增加基质 PPi。 6. 通过添加浓度不断增加的 PPi (1-20 mM) 或缬氨霉素，在等渗 KSCN 中断电条件下孵育的线粒体的膨胀逐渐增强。 7.在等渗焦磷酸钾中，最初溶胀缓慢，但随着时间的推移而加速。这种加速被 ADP 抑制，而羧基苍术苷则诱导快速肿胀。其他同渗 PPi 盐的溶胀表明，进入速率按 NH4+ > K+ > Na+ > Li+ 的顺序降低，而胆碱、四甲基铵和 Tris 则不进入。这表明，当PPi结合时，腺嘌呤核苷酸转位酶转运小单价阳离子，并且当转运蛋白处于羧基苍术苷诱导的构象时，PPi也可以被转运。 8. 结论是，Ca2+ 和丁酸盐通过 PPi 对线粒体内膜 K+ 通透性的影响，导致通电线粒体肿胀。 9. 用胰高血糖素或去氧肾上腺素治疗的大鼠的冻夹肝脏显示组织 PPi 增加了 30-50%。有人提出，Ca2+ 介导的线粒体 PPi 增加是激素处理后观察到的基质体积和总腺嘌呤核苷酸含量增加的原因。
1. The matrix pyrophosphate (PPi) content of isolated energized rat liver mitochondria incubated in the presence of ATP, Mg2+, Pi and respiratory substrates was about 100 pmol/mg of protein. 2. After incubation with sub-micromolar [Ca2+], this was increased by as much as 300%. There was a correlation between the effects of Ca2+ on PPi and on the increase in matrix volume reported previously [Halestrap, Quinlan, Whipps and Armston (1986) Biochem. J. 236, 779-787]. Half-maximal effects were seen at 0.3 .mu.M-Ca2+. 3. Coincident with these effects, the total adenine nucleotide content increased in a carboxyatractyloside-sensitive manner. 4. Incubation with 0.2-0.5 mM-butyrate induced similar but smaller effects on mitochondrial swelling and matrix PPi and total adenine nucleotide content. Addition of butyrate after Ca2+, or vice versa, caused Ca2+-induced mitochondrial swelling to stop or reverse, while matrix PPi increased 30-fold. 5. Addition of atractyloside or the omission of ATP from incubations greatly enhanced swelling induced by Ca2+ without increasing matrix PPi. 6. Swelling of mitochondria incubated under de-energized conditions in iso-osmotic KSCN was progressively enhanced by the addition of increasing concentrations of PPi (1-20 mM) or valinomycin. 7. In iso-osmotic potassium pyrophosphate swelling was slow initially, but accelerated with time. This acceleration was inhibited by ADP, whereas carboxyatractyloside induced rapid swelling. Swelling in other ios-osmotic PPi salts showed that the rate of entry decreased in the order NH4+ > K+ > Na+ > Li+, whereas choline, tetramethylammonium and Tris did not enter. It is suggested that the adenine nucleotide translocase transports small univalent cations when PPi is bound and that PPi can also be transported when the transporter is in the conformation induced by carboxyatractyloside. 8. It is concluded that Ca2+ and butyrate cause swelling of energized mitochondria through this effect of PPi on K+ permeability of the mitochondrial inner membrane. 9. Freeze-clamped livers from rats treated with glucagon or phenylephrine show 30-50% increases in tissue PPi. It is proposed that Ca2+-mediated increases in mitochondrial PPi are responsible for the increase in matrix volume and total adenine nucelotide content observed after hormone treatment.