ELECTROPHYSIOLOGICAL EFFECTS OF 4-HYDROXYNONENAL, AN ALDEHYDIC PRODUCT OF LIPID-PEROXIDATION, ON ISOLATED RAT VENTRICULAR MYOCYTES
ELECTROPHYSIOLOGICAL EFFECTS OF 4-HYDROXYNONENAL, AN ALDEHYDIC PRODUCT OF LIPID-PEROXIDATION, ON ISOLATED RAT VENTRICULAR MYOCYTES
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DOI：
10.1161/01.res.76.2.293
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发表时间：
1995-02-01
影响因子：
20.1
通讯作者：
BHATNAGAR, A
中科院分区：
文献类型：
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作者：
BHATNAGAR, A
脂质过氧化的醛类产物，例如 4-羟基壬烯醛 (4-HNE)，与氧化应激下病理变化的病因有关。为了确定 4-HNE 改变细胞兴奋性的机制，研究了其对离体大鼠心室肌细胞的影响。灌输 100 至 880 μmol/L 4-HNE 会导致肌细胞出现时间和浓度依赖性的僵硬缩短。 1 mmol/L La3+ 减少 [Ca2+](o) 和抑制跨肌膜 Ca2+ 转运并不影响 4-HNE 诱导的肌细胞僵直的程度或时间进程。用 400 μmol/L 4-HNE 灌注心肌细胞会导致动作电位持续时间增加、静息膜电位进行性去极化、心肌细胞输入电阻 (R(in)) 增加（I 相），随后导致电兴奋性丧失。持续灌注 4-HNE 导致膜超极化和 R(in) 显着降低（II 期）。R(in) 的降低与肌细胞的僵硬度一致。在全细胞电压钳实验中，灌注 4-HNE 可抑制通过内向整流器 K+ 通道 (I-K1) 的电流。 4-HNE 对 L 型 Ca2+ 电流的幅度或“衰减”速率没有影响。暴露于 4-HNE 会导致快速内向 Na+ 电流 (I-Na) 的幅度增加。 I-Na 激活和失活的稳态参数的电压依赖性转向更正的电位，从而导致窗口电流增加。 4-HNE 诱导的肌细胞僵硬伴随着与时间无关的电流的大幅增加，该电流对膜电位呈线性依赖性，并被格列本脲抑制，表明 ATP 敏感的 K+ 通道被激活。在含有 La3+ 和河豚毒素的含 Cs+ 林格氏溶液以及含 Cs+ 内部溶液（漏电流）中记录的稳态电流不受 4-HNE 的影响。灌注 4-HNE 导致细胞内非蛋白硫醇浓度显着降低，[ATP](i) 严重降低。肌细胞的能量电荷从0.9下降到0.3。这些观察结果表明 4-HNE 诱导的膜去极化可能是由于 I-K1 的抑制。 I-Na 电压依赖性的变化、I-K1 的抑制和膜去极化似乎有助于在 I 相期间观察到的动作电位的延长。[ATP] 的消耗可能是在 II 相期间观察到的变化的原因，即 ATP 敏感的 K+ 通道的激活、膜超极化、R(in) 降低和肌细胞的严格缩短。这些结果表明，脂质过氧化的稳定产物，例如 4-HNE，具有致心律失常性，并可能导致氧化应激的细胞毒性作用。
Aldehydic products of lipid peroxidation, such as 4-hydroxynonenal (4-HNE), have been implicated in the etiology of pathological changes under oxidative stress. To identify the mechanism by which 4-HNE alters cellular excitability, its effects on isolated rat ventricular myocytes were studied. Superfusion with 100 to 880 mu mol/L 4-HNE led to a time- and concentration-dependent rigor shortening of myocytes. A reduction in [Ca2+](o) and inhibition of transsarcolemmal Ca2+ transport by 1 mmol/L La3+ did not affect either the magnitude or the time course of 4-HNE-induced myocyte rigor. Superfusion of myocytes with 400 mu mol/L 4-HNE led to an increase in the action potential duration, progressive depolarization of the resting membrane potential, and an increase in the input resistance (R(in)) of the myocyte (phase I), followed by a loss of electrical excitability. Continued superfusion with 4-HNE re sulted in membrane hyperpolarization and a prominent decrease in the R(in) (phase II), The decrease in R(in) coincided with myocyte rigor. In whole-cell voltage-clamp experiments, superfusion with 4-HNE inhibited current through the inward rectifier K+ channel (I-K1). 4-HNE had no effect on either the magnitude or the rate of ''rundown'' of L-type Ca2+ currents. Exposure to 4-HNE led to an increase in the magnitude of the fast inward Na+ current (I-Na). The voltage dependence of the steady state parameters for activation and inactivation of I-Na shifted to more positive potentials, with a resultant increase in the window current. 4-HNE-induced myocyte rigor was accompanied by a large increase in time-independent currents that displayed linear dependence on the membrane potential and were inhibited by glibenclamide, suggesting activation of the ATP-sensitive K+ channel. Steady state currents recorded in Cs+-containing Ringer's solution with La3+ and tetrodotoxin and Cs+-containing internal solution (leak currents) were not affected by 4-HNE. Superfusion with 4-HNE resulted in a significant decrease in the cellular concentration of nonprotein thiols and a severe decrease in [ATP](i). The energy charge of the myocytes fell from 0.9 to 0.3. These observations indicate that 4-HNE-induced membrane depolarization may be due to an inhibition of I-K1. Changes in voltage dependence of I-Na, inhibition of I-K1 and membrane depolarization appear to contribute to the prolongation of the action potential, observed during phase I. Depletion of [ATP], may be responsible for changes observed during phase II, ie, activation of the ATP-sensitive K+ channels, membrane hyperpolarization, decrease in R(in), and rigor shortening of the myocytes. These results suggest that stable products of lipid peroxidation, such as 4-HNE, are proarrhythmic and may contribute to the cytotoxic effects of oxidative stress.