NAD(P)H fluorescence imaging of mitochondrial metabolism in contracting Xenopus skeletal muscle fibers: effect of oxygen availability.
NAD(P)H fluorescence imaging of mitochondrial metabolism in contracting Xenopus skeletal muscle fibers: effect of oxygen availability.
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非洲爪蟾骨骼肌纤维收缩过程中线粒体代谢的 NAD(P)H 荧光成像：氧利用率的影响。
DOI：
10.1152/japplphysiol.00849.2004
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Combs,ChristianA
中科院分区：
文献类型：
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作者：
Hogan,MichaelC;Stary,CreedM;Balaban,RobertS;Combs,ChristianA
根据形态和功能相关性，非洲爪蟾单骨骼肌纤维的蓝色自发荧光（351 nm 激发，450 nm 发射）被鉴定为源自线粒体 NAD(P)H。该荧光信号用于通过共焦显微镜估计工作水平转换期间分离的单个爪蟾肌纤维的氧气可用性。刺激纤维产生两个收缩期，这两个收缩期仅在灌注单纤维的溶液的 Po2 上有所不同（Po2 为 30 或 0-2 Torr；pH = 7.2）。在收缩期间，平均细胞 NAD(P)H 从低 Po2 条件下的静止状态显着增加，其中核心（内部 10%）增加的程度大于外围（外部 10%）。停止工作后，NAD(P)H 以与足以氧化多余 NAD(P)H 的氧张力一致的方式减少。相比之下，NAD(P)H 在 30 Torr Po2 下工作时显着下降。然而，与外围区域相比，NAD(P)H 氧化速率较慢，并且随着纤维核心工作的停止而显着增加，这与氧气可用性的剩余限制一致。这些结果表明爪蟾骨骼肌纤维中的蓝色自发荧光信号来自线粒体NAD(P)H，并且细胞内NAD(P)H氧化速率受到细胞外Po2的影响，即使在收缩周期期间细胞外Po2较高时也是如此。这些结果还表明，尽管氧气可用性影响 NAD(P)H 氧化速率，但它并不能阻止 NAD(P)H 在收缩开始时通过氧化磷酸化过程被氧化。
The blue autofluorescence (351 nm excitation, 450 nm emission) of single skeletal muscle fibers fromXenopuswas characterized to be originating from mitochondrial NAD(P)H on the basis of morphological and functional correlations. This fluorescence signal was used to estimate the oxygen availability to isolated singleXenopusmuscle fibers during work level transitions by confocal microscopy. Fibers were stimulated to generate two contractile periods that were only different in the Po2of the solution perfusing the single fibers (Po2of 30 or 0–2 Torr; pH = 7.2). During contractions, mean cellular NAD(P)H increased significantly from rest in the low Po2condition with the core (inner 10%) increasing to a greater extent than the periphery (outer 10%). After the cessation of work, NAD(P)H decreased in a manner consistent with oxygen tensions sufficient to oxidize the surplus NAD(P)H. In contrast, NAD(P)H decreased significantly with work in 30 Torr Po2. However, the rate of NAD(P)H oxidation was slower and significantly increased with the cessation of work in the core of the fiber compared with the peripheral region, consistent with a remaining limitation in oxygen availability. These results suggest that the blue autofluorescence signal inXenopusskeletal muscle fibers is from mitochondrial NAD(P)H and that the rate of NAD(P)H oxidation within the cell is influenced by extracellular Po2even at high extracellular Po2during the contraction cycle. These results also demonstrate that although oxygen availability influences the rate of NAD(P)H oxidation, it does not prevent NAD(P)H from being oxidized through the process of oxidative phosphorylation at the onset of contractions.