CHARACTERIZATION OF THE MITOCHONDRIAL NA+-H+ EXCHANGE - THE EFFECT OF AMILORIDE ANALOGS
CHARACTERIZATION OF THE MITOCHONDRIAL NA+-H+ EXCHANGE - THE EFFECT OF AMILORIDE ANALOGS
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DOI：
10.1016/0005-2736(88)90509-3
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发表时间：
1988-10-20
期刊：
影响因子：
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通讯作者：
FONYO, A
中科院分区：
文献类型：
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作者：
KAPUS, A;LUKACS, GL;FONYO, A
研究了大鼠心、肝线粒体内膜Na+-H+交换活性的动力学性质和抑制剂敏感性。(1) Na+诱导的线粒体H+外排遵循Michaelis-Menten动力学。在心脏线粒体中，Na+的Km为24。4 mM， Vmax为4.5 +-。1.4 nmol H+/mg蛋白质/ s （n = 6）。在肝脏线粒体（Km = 31 .+-）中得到了基本相似的值。2mm, Vmax = 5.3 .+-。(2) Li+被证明是一种底物（Km = 5.9 mM, Vmax = 2.3 nmol H+/mg protein / s）和相对于Na+的一种有效的竞争性抑制剂（Ki .apprxeq. 1）。0.7毫米)。(3)外部H+竞争性地抑制线粒体Na+-H+交换。(4) amiloride的两种苯甲酰胺衍生物，5 -（n -4-氯苯基）- n -（2”，4”-二甲基）苯甲酰胺和3”，5”-双（三氟甲基）苯甲酰胺是线粒体Na+- h +交换的有效抑制剂（约50%的抑制作用）。60 .mu。M在15mm Na+存在下)。(5)阿米洛利的3种5-氨基类似物是质膜上非常强的Na+-H+交换阻滞剂，但对线粒体Na+-H+交换的抑制作用较弱。(6)结果表明，线粒体和质膜反转运蛋白代表不同的分子实体。
The kinetic properties and inhibitor sensitivity of the Na+-H+ exchange activity present in the inner membrane of rat heart and liver mitochondria were studied. (1) Na+-induced H+ efflux from mitochondria followed Michaelis-Menten kinetics. In heart mitochondria, the Km for Na+ was 24 .+-. 4 mM and the Vmax was 4.5 .+-. 1.4 nmol H+/mg protein per s (n = 6). Basically similar values were obtained in liver mitochondria (Km = 31 .+-. 2 mM, Vmax = 5.3 .+-. 0.2 nmol H+/mg protein per s, n = 4). (2) Li+ proved to be a substrate (Km = 5.9 mM, Vmax = 2.3 nmol H+/mg protein per s) and a potent competitive inhibitor with respect to Na+ (Ki .apprxeq. 0.7 mM). (3) External H+ inhibited the mitochondrial Na+-H+ exchange competitively. (4) Two benzamil derivatives of amiloride, 5-(N-4-chlorobenzyl)-N-(2'',4''-dimethyl)benzamil and 3'',5''-bis(trifluromethyl)benzamil was effective inhibitors of the mitochondrial Na+-H+ exchange (50% inhibition was attained by approx. 60 .mu.M in the presence of 15 mM Na+). (5) Three 5-amino analogues of amiloride, which are very strong Na+-H+ exchange blockers on the plasma membrane, exerted only weak inhibitory activity on the mitochondrial Na+-H+ exchange. (6) The results indicate that the mitochondrial and the plasma membrane antiporters represent distinct molecular entities.