Schnellmann R G, Cross T J, Lock E A
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602.
Toxicol Appl Pharmacol. 1989 Sep 15;100(3):498-505. doi: 10.1016/0041-008x(89)90297-4.
A very early event in the toxicity of pentachlorobutadienyl-L-cysteine (PCBC) to rabbit renal proximal tubules is uncoupling of oxidative phosphorylation (R.G. Schnellmann, E. A. Lock, and L. J. Mandel (1986), Toxicologist 6, 176; (1987), Toxicol. Appl. Pharmacol. 90, 521). The mechanism of PCBC uncoupling of mitochondrial oxidative phosphorylation has been investigated using isolated rabbit renal cortical mitochondria (RCM). PCBC increased state 4 respiration of RCM respiring on pyruvate/malate or succinate in a concentration (10-100 microM)- and time (1-5 min)-dependent manner. PCBC also increased state 4 respiration in the presence of oligomycin, an inhibitor of F0F1-ATPase. The effect of PCBC on mitochondrial proton permeability was determined by measuring passive mitochondrial swelling. After a 2-min exposure to PCBC, RCM swelled when placed in NH4Cl or NaCl, but not KCl or sucrose. The protonophore carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP) (1 microM) produced similar effects. After 5 min, RCM swelled when placed in NH4Cl, NaCl, or KCl, but not in sucrose. Aminooxyacetic acid, an inhibitor of cysteine conjugate beta-lyase, blocked the effects of PCBC on respiration, indicating that PCBC can be metabolized by RCM to produce RCM toxicity. These results show that PCBC initially uncouples oxidative phosphorylation by dissipating the proton gradient. Subsequently, additional ion permeabilities occur. These results are in complete agreement with previous observations in rabbit renal proximal tubule suspensions.
五氯丁二烯基-L-半胱氨酸（PCBC）对兔肾近端小管产生毒性作用的一个非常早期的事件是氧化磷酸化的解偶联（R.G.施内尔曼、E.A.洛克和L.J.曼德尔（1986年），《毒理学家》6卷，176页；（1987年），《毒理学与应用药理学》90卷，521页）。已使用分离的兔肾皮质线粒体（RCM）研究了PCBC使线粒体氧化磷酸化解偶联的机制。PCBC以浓度（10 - 100微摩尔）和时间（1 - 5分钟）依赖性方式增加了以丙酮酸/苹果酸或琥珀酸为呼吸底物的RCM的状态4呼吸。在存在F0F1 - ATP酶抑制剂寡霉素的情况下，PCBC也增加了状态4呼吸。通过测量线粒体被动肿胀来确定PCBC对线粒体质子通透性的影响。暴露于PCBC 2分钟后，当置于氯化铵或氯化钠中时RCM肿胀，但置于氯化钾或蔗糖中时不肿胀。质子载体羰基氰化物对三氟甲氧基苯腙（FCCP）（1微摩尔）产生类似效果。5分钟后，当置于氯化铵、氯化钠或氯化钾中时RCM肿胀，但置于蔗糖中时不肿胀。半胱氨酸共轭β-裂合酶抑制剂氨基氧乙酸阻断了PCBC对呼吸的影响，表明PCBC可被RCM代谢以产生RCM毒性。这些结果表明，PCBC最初通过耗散质子梯度使氧化磷酸化解偶联。随后，出现了额外的离子通透性。这些结果与先前在兔肾近端小管悬浮液中的观察结果完全一致。
