Mitochondrial matrix K+ flux independent of large-conductance Ca2+-activated K+ channel opening
Mitochondrial matrix K+ flux independent of large-conductance Ca2+-activated K+ channel opening
复制标题
DOI：
10.1152/ajpcell.00468.2009
复制
发表时间：
2010-03-01
影响因子：
5.5
通讯作者：
Camara, Amadou K. S.
中科院分区：
文献类型：
--
作者：
Aldakkak, Mohammed;Stowe, David F.;Camara, Amadou K. S.
Aldakkak M，斯托，Cheng Q，Kwok W，Camara AK.线粒体基质K+通量独立于大电导Ca 2+激活的K+通道开放。美国生理学杂志细胞生理学298：C530-C541，2010年。首次发表于2010年1月6日; doi：10.1152/ajpcell.00468.2009。线粒体内膜大电导钙激活钾通道（BKCa）可能在心肌缺血再灌注损伤中起保护作用。NS 1619（30 μ M），BKCa通道的激活剂，显示出增加呼吸和刺激活性氧的产生，在离体的心脏线粒体与琥珀酸供能。在这里，我们测试了NS 1619改变豚鼠心脏分离的线粒体中基质K+、H+和肿胀的作用。我们发现，30 μ M的NS 1619没有改变基质K+，H+，和肿胀，但50和100 μ M的NS 1619引起浓度依赖性增加基质K+流入（PBFI荧光）只有当奎宁存在，以阻止K+/H+交换（KHE），这是伴随着增加线粒体基质体积（光散射）。基质pH值（BCECF荧光）略有下降，50和100 μ M NS 1619，但显着更多，所以当奎宁存在。NS 1619（100 μ M）引起脂质双层的显着泄漏，这是增强奎宁的存在下。K+离子载体缬氨霉素（0.25 nM），如NS 1619增加基质体积和增加K+流入奎宁的存在下，引起基质碱化，然后酸化时奎宁是不存在的，只有碱化时奎宁是存在的。如果K+通过活化的KHE立即被H+交换，则基质K+流入将刺激H+通过KHE流入并引起基质酸化。我们的研究结果表明，KHE并没有立即激活NS 1619诱导的K+内流，NS 1619诱导基质K+和H+内流通过一种非特异性的运输机制，并与奎宁的增强是不是由于KHE的阻断，但奎宁的非特异性作用，以增强电流泄漏的NS 1619。
Aldakkak M, Stowe DF, Cheng Q, Kwok W, Camara AK. Mitochondrial matrix K+ flux independent of large-conductance Ca2+-activated K+ channel opening. Am J Physiol Cell Physiol 298: C530-C541, 2010. First published January 6, 2010; doi: 10.1152/ajpcell.00468.2009.-Large-conductance Ca2+-activated K+ channels (BKCa) in the inner mitochondrial membrane may play a role in protecting against cardiac ischemia-reperfusion injury. NS1619 (30 mu M), an activator of BKCa channels, was shown to increase respiration and to stimulate reactive oxygen species generation in isolated cardiac mitochondria energized with succinate. Here, we tested effects of NS1619 to alter matrix K+, H+, and swelling in mitochondria isolated from guinea pig hearts. We found that 30 mu M NS1619 did not change matrix K+, H+, and swelling, but that 50 and 100 mu M NS1619 caused a concentration-dependent increase in matrix K+ influx (PBFI fluorescence) only when quinine was present to block K+/H+ exchange (KHE); this was accompanied by increased mitochondrial matrix volume (light scattering). Matrix pH (BCECF fluorescence) was decreased slightly by 50 and 100 mu M NS1619 but markedly more so when quinine was present. NS1619 (100 mu M) caused a significant leak in lipid bilayers, and this was enhanced in the presence of quinine. The K+ ionophore valinomycin (0.25 nM), which like NS1619 increased matrix volume and increased K+ influx in the presence of quinine, caused matrix alkalinization followed by acidification when quinine was absent, and only alkalinization when quinine was present. If K+ is exchanged instantly by H+ through activated KHE, then matrix K+ influx should stimulate H+ influx through KHE and cause matrix acidification. Our results indicate that KHE is not activated immediately by NS1619-induced K+ influx, that NS1619 induces matrix K+ and H+ influx through a nonspecific transport mechanism, and that enhancement with quinine is not due to the blocking of KHE, but to a nonspecific effect of quinine to enhance current leak by NS1619.