Boveris Alberto, Valdez Laura B, Zaobornyj Tamara, Bustamante Juanita
Laboratory of Free Radical Biology, School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina.
Biochim Biophys Acta. 2006 May-Jun;1757(5-6):535-42. doi: 10.1016/j.bbabio.2006.02.010. Epub 2006 Mar 20.
Mitochondria isolated from rat heart, liver, kidney and brain (respiratory control 4.0-6.5) release NO and H2O2 at rates that depend on the mitochondrial metabolic state: releases are higher in state 4, about 1.7-2.0 times for NO and 4-16 times for H2O2, than in state 3. NO release in rat liver mitochondria showed an exponential dependence on membrane potential in the range 55 to 180 mV, as determined by Rh-123 fluorescence. A similar behavior was reported for mitochondrial H2O2 production by [S.S. Korshunov, V.P. Skulachev, A.A. Starkov, High protonic potential actuates a mechanism of production of reactive oxygen species in mitochondria. FEBS Lett. 416 (1997) 15_18.]. Transition from state 4 to state 3 of brain cortex mitochondria was associated to a decrease in NO release (50%) and in membrane potential (24-53%), this latter determined by flow cytometry and DiOC6 and JC-1 fluorescence. The fraction of cytosolic NO provided by diffusion from mitochondria was 61% in heart, 47% in liver, 30% in kidney, and 18% in brain. The data supports the speculation that NO and H2O2 report a high mitochondrial energy charge to the cytosol. Regulation of mtNOS activity by membrane potential makes mtNOS a regulable enzyme that in turn regulates mitochondrial O2 uptake and H2O2 production.
从大鼠心脏、肝脏、肾脏和大脑分离出的线粒体（呼吸控制率为4.0 - 6.5）释放一氧化氮（NO）和过氧化氢（H₂O₂）的速率取决于线粒体的代谢状态：在状态4下的释放量更高，NO的释放量约为状态3下的1.7 - 2.0倍，H₂O₂的释放量为状态3下的4 - 16倍。通过罗丹明123荧光测定，大鼠肝脏线粒体中NO的释放对55至180 mV范围内的膜电位呈指数依赖性。[S.S. Korshunov, V.P. Skulachev, A.A. Starkov, High protonic potential actuates a mechanism of production of reactive oxygen species in mitochondria. FEBS Lett. 416 (1997) 15_18.]报道了线粒体H₂O₂产生的类似行为。大脑皮质线粒体从状态4转变为状态3与NO释放量减少（50%）和膜电位降低（24 - 53%）有关，后者通过流式细胞术以及DiOC6和JC - 1荧光测定。线粒体扩散提供的胞质NO比例在心脏中为61%，在肝脏中为47%，在肾脏中为30%，在大脑中为18%。这些数据支持了以下推测：NO和H₂O₂向细胞质报告线粒体的高能荷状态。膜电位对线粒体一氧化氮合酶（mtNOS）活性的调节使mtNOS成为一种可调节的酶，进而调节线粒体对氧气的摄取和H₂O₂的产生。
