Calcium-mediated coupling between mitochondrial substrate dehydrogenation and cardiac workload in single guinea-pig ventricular myocytes
Calcium-mediated coupling between mitochondrial substrate dehydrogenation and cardiac workload in single guinea-pig ventricular myocytes
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DOI：
10.1016/j.yjmcc.2005.12.012
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发表时间：
2006-03-01
影响因子：
5
通讯作者：
Matsuoka, S
中科院分区：
文献类型：
--
作者：
Jo, H;Noma, A;Matsuoka, S
我们测量线粒体NADIA自发荧光或Ca 2+使用Rhod-2，同时在离体豚鼠心室肌细胞的细胞缩短。当频率和幅度的抽搐缩短（工作强度）增加，提高刺激频率从0.1到3.3 Hz的增量步骤，稳定水平的NADH信号增加频率依赖性的方式。线粒体Ca ~（2+）也随着劳动强度的增加而增加。应用线粒体Ca ~（2+）单向转运体抑制剂Ru 360，大大减弱了NADH荧光和线粒体Ca ~（2+）的反应。线粒体内Ca ~（2+）的增加缓慢，t（12）= 12 s，NADH信号无明显的周期性变化。当施加从0.1到3.3 Hz的阶跃变化刺激时，NADH信号首先降低到对照水平的83%，然后增加到对照水平的155%。回到0后。1 Hz时，NADH信号在下降到对照水平之前显示出过冲。双相起始时间过程很好地解释了延迟的Ca 2+激活的底物脱氢叠加在ATP合成的反馈控制，而偏移时间过程与延迟失活的脱氢。使用氧化磷酸化连接到心脏兴奋收缩模型的计算机模拟很好地重建了NADH的反应。该模型模拟预测，底物脱氢的活化提供了ATP合成的驱动力的23%，以满足刺激从0.1到3.3 Hz的跳跃引起的增加的工作量，其余的77%由反馈控制提供。(c)2006爱思唯尔有限公司保留所有权利。
We measured mitochondrial NADIA autofluorescence or Ca2+ using Rhod-2, simultaneously with cell shortening in isolated guinea-pig ventricular myocytes. When both frequency and amplitude of twitch shortening (work intensity) were increased by raising stimulus frequency in incremental steps from 0.1 to 3.3 Hz, the steady level of NADH signal increased in a frequency-dependent manner. Mitochondrial Ca2+ also increased with increasing work intensity. Applying Ru360, an inhibitor of mitochondrial Ca2+ uniporter, largely attenuated the response of both NADH fluorescence and mitochondrial Ca2+. The increase in mitochondrial Ca2+ was slow with t(1/2) = similar to 12 s and no obvious cyclic changes were observed in the NADH signal. When a step change from 0.1 to 3.3 Hz stimulation was applied, the NADH signal first decreased to 83% and then increased to 155% of the control level. Upon returning to 0. 1 Hz, the NADH signal showed an overshoot before declining to the control level. The biphasic onset time course was well explained by the delayed Ca2+ activation of the substrate dehydrogenation superimposed on the feedback control of the ATP synthesis, while the offset time Course with a delayed deactivation of dehydrogenation. A computer simulation using an oxidative phosphorylation linked to the cardiac excitation contraction model well reconstructed the response of NADH. This model simulation predicts that the activation of substrate dehydrogenation provides similar to 23% of driving force of the ATP synthesis to meet the increased workload induced by the jump of stimulus from 0.1 to 3.3 Hz, and remaining similar to 77% is supplied by the feedback control. (c) 2006 Elsevier Ltd. All rights reserved.