Nieminen A L, Saylor A K, Herman B, Lemasters J J
Department of Cell Biology and Anatomy, University of North Carolina at Chapel Hill 27599-7090.
Am J Physiol. 1994 Jul;267(1 Pt 1):C67-74. doi: 10.1152/ajpcell.1994.267.1.C67.
The importance of ATP depletion and mitochondrial depolarization in the toxicity of cyanide, oligomycin, and carbonyl cyanide m-cholorophenylhydrazone (CCCP), an uncoupler, was evaluated in rat hepatocytes. Oligomycin, an inhibitor of the reversible mitochondrial ATP synthase (F1F0-adenosinetriphosphatase), caused dose-dependent cell killing with 0.1 microgram/ml being the minimum concentration causing the maximum cell killing. Oligomycin also caused rapid ATP depletion without causing mitochondrial depolarization. Fructose (20 mM), a potent glycolytic substrate in liver, protected completely against oligomycin toxicity. CCCP (5 microM) also caused rapid killing of hepatocytes. Fructose retarded cell death caused by CCCP but failed to prevent lethal cell injury. Although oligomycin (1.0 microgram/ml) was lethally toxic by itself, in the presence of fructose it protected completely against CCCP-induced cell killing. Cyanide (2.5 mM), an inhibitor of mitochondrial respiration, caused rapid cell killing that was reversed by fructose. CCCP completely blocked fructose protection against cyanide, causing mitochondrial depolarization and rapid ATP depletion. In the presence of fructose and cyanide, oligomycin protected cells against CCCP-induced ATP depletion and cell death but did not prevent mitochondrial depolarization. In every instance, cell killing was associated with ATP depletion, whereas protection against lethal cell injury was associated with preservation of ATP. In conclusion, protection by fructose against toxicity of cyanide, oligomycin, and CCCP was mediated by glycolytic ATP formation rather than by preservation of the mitochondrial membrane potential. These findings support the hypothesis that inhibition of cellular ATP formation is a crucial event in the progression of irreversible cell injury.
在大鼠肝细胞中评估了ATP耗竭和线粒体去极化在氰化物、寡霉素及羰基氰化物间氯苯腙(CCCP,一种解偶联剂)毒性作用中的重要性。寡霉素是可逆性线粒体ATP合酶(F1F0 - 三磷酸腺苷酶)的抑制剂,可引起剂量依赖性细胞死亡,0.1微克/毫升是导致最大细胞死亡的最低浓度。寡霉素还可导致快速的ATP耗竭,但不会引起线粒体去极化。果糖(20毫摩尔)是肝脏中一种有效的糖酵解底物,可完全保护细胞免受寡霉素毒性的影响。CCCP(5微摩尔)也可导致肝细胞快速死亡。果糖可延缓CCCP引起的细胞死亡,但未能防止致命的细胞损伤。尽管寡霉素(1.0微克/毫升)本身具有致命毒性,但在果糖存在的情况下,它可完全保护细胞免受CCCP诱导的细胞死亡。氰化物(2.5毫摩尔)是线粒体呼吸的抑制剂,可引起快速的细胞死亡,果糖可使其逆转。CCCP完全阻断了果糖对氰化物的保护作用,导致线粒体去极化和快速的ATP耗竭。在果糖和氰化物存在的情况下,寡霉素可保护细胞免受CCCP诱导的ATP耗竭和细胞死亡,但不能防止线粒体去极化。在每种情况下,细胞死亡都与ATP耗竭有关,而对致命细胞损伤的保护则与ATP的保存有关。总之,果糖对氰化物、寡霉素和CCCP毒性的保护作用是由糖酵解产生ATP介导的,而不是通过维持线粒体膜电位实现的。这些发现支持了这样一种假说,即细胞ATP生成的抑制是不可逆细胞损伤进展中的一个关键事件。