Henry T R, Solem L E, Wallace K B
Department of Pharmacology, School of Medicine, University of Minnesota, Duluth 55812, USA.
J Toxicol Environ Health. 1995 Aug;45(4):489-504. doi: 10.1080/15287399509532011.
It is well established that menadione, 2-methyl-1,4-naphthoquinone, impairs the ability of rat liver mitochondria to accumulate and retain calcium. However, it remains unclear whether this reflects inhibition of mitochondrial calcium uptake or stimulation of calcium release by menadione. The purpose of the current investigation was to determine whether interference with mitochondrial calcium homeostasis by menadione reflects a selective activation of the cyclosporine A-sensitive pore, independent of actions on other mitochondrial calcium channels. Mitochondrial calcium flux was monitored using the metallochromic dye arsenazo III. Treatment of mitochondria with menadione caused a concentration-dependent decrease in net calcium accumulation followed by a delayed release of the accumulated calcium and concurrent mitochondrial swelling. Both the maximum steady-state accumulation of calcium and the delay preceding calcium release decreased as a function of calcium concentration. The release of calcium did not occur via the Na+/Ca2+ antiport or reversal of the uptake uniport, as neither diltiazem nor ruthenium red prevented the menadione-stimulated calcium release. In contrast, cyclosporine A, a potent inhibitor of the permeability transition pore, completely inhibited menadione-induced calcium release and the associated swelling. Furthermore, the menadione-induced inhibition of calcium accumulation was completely prevented in the presence of cyclosporine A, indicating a selective stimulation of calcium release by menadione, rather than inhibition of calcium uptake. These data provide the first definitive description of a specific action of menadione to stimulate mitochondrial calcium release through a cyclosporine A-sensitive pathway, independent of altering the regulation of other recognized calcium channels associated with the inner mitochondrial membrane.
维生素K3（2-甲基-1,4-萘醌）损害大鼠肝线粒体积累和保留钙的能力，这一点已得到充分证实。然而，目前尚不清楚这是反映了维生素K3对线粒体钙摄取的抑制作用，还是对钙释放的刺激作用。本研究的目的是确定维生素K3对线粒体钙稳态的干扰是否反映了环孢素A敏感孔的选择性激活，而与对其他线粒体钙通道的作用无关。使用金属显色染料偶氮胂III监测线粒体钙通量。用维生素K3处理线粒体导致净钙积累呈浓度依赖性下降，随后积累的钙延迟释放并伴有线粒体肿胀。钙的最大稳态积累量和钙释放前的延迟时间均随钙浓度的变化而降低。钙的释放并非通过Na+/Ca2+反向转运或摄取单向转运的逆转发生，因为地尔硫卓和钌红均不能阻止维生素K3刺激的钙释放。相反，环孢素A（一种通透性转换孔的有效抑制剂）完全抑制了维生素K3诱导的钙释放及相关肿胀。此外，在存在环孢素A的情况下，维生素K3对钙积累的抑制作用被完全阻止，这表明维生素K3选择性地刺激了钙释放，而非抑制钙摄取。这些数据首次明确描述了维生素K3通过环孢素A敏感途径刺激线粒体钙释放的具体作用，且该作用与改变线粒体内膜相关的其他公认钙通道的调节无关。
