EFFECTS OF SPERMINE ON MITOCHONDRIAL CA-2+ TRANSPORT AND THE RANGES OF EXTRAMITOCHONDRIAL CA-2+ TO WHICH THE MATRIX CA-2+-SENSITIVE DEHYDROGENASES RESPOND
EFFECTS OF SPERMINE ON MITOCHONDRIAL CA-2+ TRANSPORT AND THE RANGES OF EXTRAMITOCHONDRIAL CA-2+ TO WHICH THE MATRIX CA-2+-SENSITIVE DEHYDROGENASES RESPOND
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DOI：
10.1042/bj2640167
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发表时间：
1989-11-15
影响因子：
4.1
通讯作者：
MCCORMACK, JG
中科院分区：
文献类型：
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作者：
MCCORMACK, JG
1. 精胺此前曾被报道为线粒体 Ca2+ 吸收的激活剂 [Nicchitta 和 Williamson (1984) J. Biol.化学。 259、12978-12983]。目前对大鼠心脏、肝脏和肾线粒体的研究证实了这一点，通过使用 Ca2+ 敏感的线粒体内脱氢酶（丙酮酸 NAD+-异柠檬酸和 2-氧戊二酸脱氢酶）的活性作为基质 Ca2+ 的探针，并且通过使用包埋的 fura-2 对心脏线粒体进行研究。 2. 也如先前发现的那样[Damuni、Humphreys 和 Reed (1984) Biochem。生物物理学。资源。交流。 124, 95-99]，精胺激活提取的丙酮酸脱氢酶磷酸磷酸酶。然而，发现它对提取的 NAD+-异柠檬酸或 2-酮戊二酸脱氢酶完全没有影响。它对未偶联线粒体中酶的活性也没有影响。 3. 精胺明显激活45Ca。 4. 精胺（有效 Km 值约为 0.2-0.4 mM）引起约。在所有组织的偶联线粒体中激活 Ca2+ 敏感基质酶时，线粒体外 Ca2+ 的有效范围减少 2-3 倍。精胺的作用似乎在很大程度上独立于线粒体 Ca2+ 转运的其他效应物，例如 Mg2+（摄取抑制剂）和 Na+（排出促进剂）。 5.在大多数生理情况下，将线粒体与Na+和Mg2+一起孵育，饱和精胺(2mM)的存在导致基质酶激活的有效线粒体外Ca2+范围为约30-50nM至约800-1200nM，半最大效应约为250-400nM-Ca2+。讨论了这些发现对基质和线粒体外 Ca2+ 调节的影响。
1. Spermine has previously been reported to be an activator of mitochondrial Ca2+ uptake [Nicchitta and Williamson (1984) J. Biol. Chem. 259, 12978-12983]. This is confirmed in the present studies on rat heart, liver and kidney mitochondria by using the activities of the Ca2+-sensitive intramitochondrial dehydrogenases (pyruvate NAD+-isocitrate and 2-oxoglutarate dehydrogenases) as probes for matrix Ca2+, and also, for the heart mitochondria, by using entrapped fura-2. 2. As also found previously [Damuni, Humphreys and Reed (1984) Biochem. Biophys. Res. Commun. 124, 95-99], spermine activated extracted pyruvate dehydrogenase phosphate phosphatase. However, it was found to have no effects at all on the extracted NAD+-isocitrate or 2-oxoglutarate dehydrogenases. It also had no effects on activities of the enzymes in uncoupled mitochondria. 3. Spermine clearly activated 45Ca. 4. Spermine (with effective Km values of around 0.2-0.4 mM) caused an approx. 2-3-fold decrease in the effective ranges of extramitochondrial Ca2+ in the activation of the Ca2+-sensitive matrix enzymes in coupled mitochondria from all of the tissues. The effects of spermine appeared to be largely independent of the other effectors of mitochondrial Ca2+ transport, such as Mg2+ (inhibitor of uptake) and Na+ (promoter of egress). 5. In the most physiological circumstance, coupled mitochondria incubated with Na+ and Mg2+, the presence of saturating spermine (2 mM) resulted in an effective extramitochondrial Ca2+ range for matrix enzyme activation of from about 30-50 nM up to about 800-1200 nM, with half-maximal effects around 250-400 nM-Ca2+. The implications of these findings for the regulation of matrix andextramitochondrial Ca2+ are discussed.