Spivey J R, Bronk S F, Gores G J
Department of Internal Medicine, Mayo Medical School, Rochester, Minnesota 55905.
J Clin Invest. 1993 Jul;92(1):17-24. doi: 10.1172/JCI116546.
Chenodeoxycholate is toxic to hepatocytes, and accumulation of chenodeoxycholate in the liver during cholestasis may potentiate hepatocellular injury. However, the mechanism of hepatocellular injury by chenodeoxycholate remains obscure. Our aim was to determine the mechanism of cytotoxicity by chenodeoxycholate in rat hepatocytes. At a concentration of 250 microM, glycochenodeoxycholate was more toxic than either chenodeoxycholate or taurochenodeoxycholate. Cellular ATP was 86% depleted within 30 min after addition of glycochenodeoxycholate. Fructose, a glycolytic substrate, maintained ATP concentrations at 50% of the initial value and protected against glycochenodeoxycholate cytotoxicity. ATP depletion in the absence of a glycolytic substrate suggested impairment of mitochondrial function. Indeed, glycochenodeoxycholate inhibited state 3 respiration in digitonin-permeabilized cells in a dose-dependent manner. After ATP depletion, a sustained rise in cytosolic free calcium (Cai2+) was observed. Removal of extracellular Ca2+ abolished the rise in Cai2+, decreased cellular proteolysis, and protected against cell killing by glycochenodeoxycholate. The results suggest that glycochenodeoxycholate cytotoxicity results from ATP depletion followed by a subsequent rise in Cai2+. The rise in Cai2+ leads to an increase in calcium-dependent degradative proteolysis and, ultimately, cell death. We conclude that glycochenodeoxycholate causes a bioenergetic form of lethal cell injury dependent on ATP depletion analogous to the lethal cell injury of anoxia.
鹅去氧胆酸盐对肝细胞有毒性，胆汁淤积时鹅去氧胆酸盐在肝脏中的蓄积可能会加重肝细胞损伤。然而，鹅去氧胆酸盐导致肝细胞损伤的机制仍不清楚。我们的目的是确定鹅去氧胆酸盐在大鼠肝细胞中的细胞毒性机制。在浓度为250微摩尔时，甘氨鹅去氧胆酸盐比鹅去氧胆酸盐或牛磺鹅去氧胆酸盐毒性更大。加入甘氨鹅去氧胆酸盐后30分钟内，细胞内三磷酸腺苷（ATP）消耗了86%。果糖作为一种糖酵解底物，可使ATP浓度维持在初始值的50%，并保护细胞免受甘氨鹅去氧胆酸盐的细胞毒性作用。在没有糖酵解底物的情况下ATP消耗提示线粒体功能受损。事实上，甘氨鹅去氧胆酸盐以剂量依赖的方式抑制洋地黄皂苷通透细胞中的状态3呼吸。ATP消耗后，观察到细胞溶质游离钙（Cai2+）持续升高。去除细胞外Ca2+可消除Cai2+的升高，减少细胞蛋白水解，并保护细胞免受甘氨鹅去氧胆酸盐的细胞杀伤作用。结果表明，甘氨鹅去氧胆酸盐的细胞毒性是由ATP消耗随后Cai2+升高所致。Cai2+的升高导致钙依赖性降解性蛋白水解增加，最终导致细胞死亡。我们得出结论，甘氨鹅去氧胆酸盐导致一种依赖于ATP消耗的生物能形式的致死性细胞损伤，类似于缺氧的致死性细胞损伤。
