MITOCHONDRIAL INJURY - AN EARLY EVENT IN CISPLATIN TOXICITY TO RENAL PROXIMAL TUBULES
MITOCHONDRIAL INJURY - AN EARLY EVENT IN CISPLATIN TOXICITY TO RENAL PROXIMAL TUBULES
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DOI：
10.1152/ajprenal.1990.258.5.f1181
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发表时间：
1990-05-01
影响因子：
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通讯作者：
GULLANS, SR
中科院分区：
文献类型：
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作者：
BRADY, HR;KONE, BC;GULLANS, SR
为探讨顺铂对兔近端小管功能的早期影响，对兔近端小管悬液的氧耗量(QO2)和K+净转运进行了研究。顺铂对QO2的抑制呈剂量依赖性，起效时间延迟。[暴露40min，阈值浓度10(-4)M，抑制常数(Ki)=10(-3)M；暴露4h，阈值浓度3×10(-5)M，Ki=10(-4)M]，顺铂抑制所需浓度随暴露时间的延长而降低。哇巴因敏感和不敏感的QO2均降低，表明所有腺苷三磷酸酶均受到抑制，包括Na(+)-K(+)-ATPase活性。哇巴因敏感的净K+转运和胞浆K+含量平行下降，证实了后一种观察结果。经顺铂处理的肾小管低渗裂解制备的细胞膜Na(+)-K(+)-ATPase活性无明显变化，提示间接的胞浆依赖的酶抑制机制。在顺铂处理的小管上，制霉菌素刺激的QO2减少，排除了抑制Na+进入的损伤机制，提示线粒体损伤。后者通过测量完整细胞中的羰基氰化物-间氯苯肼(CCCP)解偶联的QO2和洋地黄素通透性小管中ADP刺激的(状态3)QO2而得到证实。此外，通过使用CCCP和制霉菌素最大限度地刺激线粒体呼吸，可以在基础QO2和K+转运明显正常的情况下显示线粒体损伤。这些数据表明，线粒体损伤是顺铂对近端小管毒性的一个中心事件。
Oxygen consumption (QO2) and net K+ transport were studied in rabbit proximal tubule suspensions to define the early effects of cisplatin on proximal tubule function. Cisplatin caused dose-dependent inhibition of QO2, which was delayed in onset. The concentration of cisplatin required for inhibition decreased as the duration of exposure was increased [40-min exposure, threshold concentration of 10(-4) M, inhibitor constant (Ki) of 10(-3) M; 4-h exposure, threshold concentration of 3 X 10(-5) M, Ki of 10(-4) M]. Both ouabain-sensitive and ouabain-insensitive QO2 were reduced, indicating inhibition of all adenosinetriphosphatases, including Na(+)- K(+)-ATPase activity. There was a parallel fall in ouabain-sensitive net K+ transport and cytosolic K+ content, confirming the latter observation. Na(+)-K(+)-ATPase activity was unchanged in cell membranes prepared by hypotonic lysis from cisplatin-treated tubules, indicating an indirect cytosol-dependent mechanism of enzyme inhibition. Nystatin-stimulated QO2 was reduced in cisplatin-treated tubules, excluding inhibition of Na+ entry as the mechanism of injury and suggesting mitochondrial injury. The latter was confirmed by measurement of carbonylcyanide-m-chlorophenylhydrazone (CCCP)-uncoupled QO2 in intact cells and ADP-stimulated (state 3) QO2 in digitonin-permeabilized tubules. Furthermore, by maximally stimulating mitochondrial respiration with CCCP and nystatin, it was possible to demonstrate mitochondrial injury at a time when basal QO2 and K+ transport were apparently normal. These data suggest that mitochondrial injury is a central event in cisplatin toxicity to the proximal tubule.