Maintenance of cellular acidification in cyanide-treated hepatocytes results from inhibition of Na+/H+ exchange.
Maintenance of cellular acidification in cyanide-treated hepatocytes results from inhibition of Na+/H+ exchange.
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氰化物处理的肝细胞中细胞酸化的维持是由于 Na /H 交换的抑制。
DOI：
10.1152/ajpgi.1994.266.5.g892
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
Weinman,SA
中科院分区：
文献类型：
--
作者：
SchoeneckerJr,JA;Weinman,SA
代谢抑制剂或缺氧对呼吸的抑制伴随着细胞内酸化。虽然已知这种酸化在缺氧期间促进细胞存活，但对其机制知之甚少。鉴于Na+/H+交换是已知的pH调节在正常肝细胞的主要组成部分，本研究的目的是确定线粒体呼吸抑制细胞内pH（pHi）调节和Na+/H+交换的影响。氰化物（CN-; 5 mM）加果糖（20 mM）用作缺氧性酸中毒模型。用定量荧光显微术测量加载有pH指示剂2 ′，7 ′-双-（2-羧乙基）-5，6-羧基荧光素的细胞的pHi。在对照细胞中，pHi为7.09 +/- 0.01 SE（n = 106）。在CN（-）-果糖中60分钟后，pHi降至6.74 +/- 0.01（n = 129，P < 0.001）。在两种条件下，通过短暂暴露和去除20 mM NH 4Cl进行酸加载后，测定pHi恢复率（表示为mmol H+·l-1·min-1）。对照和CN（-）处理的细胞分别恢复到3.59 +/- 0.25（n = 42）和0.69 +/- 0.09（n = 38，P < 0.001）。在不存在CN-的情况下，阿米洛利处理（1 mM）降低了pHi恢复，类似于CN-引起的pHi恢复（0.34 +/-0.07，n = 14）。CN（-）-处理的细胞暴露于阿米洛利没有表现出额外的抑制（流出率0.65 +/- 0.11，n = 27），表明抑制是针对Na+/H+交换。CN去除20分钟后，CN（-）处理的细胞恢复了从酸负荷中恢复的能力，从而证明了这种作用的可逆性。（250字处删节）
Inhibition of respiration by metabolic inhibitors or hypoxia is accompanied by intracellular acidification. Although this acidification is known to promote cell survival during hypoxia, little is known about its mechanism. Given that the Na+/H+ exchanger is known to be a major component of pH regulation in normal hepatocytes, the aim of this study was to determine the effects of inhibition of mitochondrial respiration on intracellular pH (pHi) regulation and Na+/H+ exchange. Cyanide (CN-; 5 mM) plus fructose (20 mM) were used as a model of hypoxic acidosis. pHi was measured with quantitative fluorescence microscopy of cells loaded with the pH indicator, 2',7'-bis-(2-carboxyethyl)-5,6-carboxyfluorescein. In control cells, pHi was 7.09 +/- 0.01 SE (n = 106). After 60 min in CN(-)-fructose, pHi fell to 6.74 +/- 0.01 (n = 129, P < 0.001). The pHi recovery rate (expressed as mmol H+.l-1.min-1) was determined under both conditions after acid loading by transient exposure and removal of 20 mM NH4Cl. Control and CN(-)-treated cells recovered at 3.59 +/- 0.25 (n = 42) and 0.69 +/- 0.09 (n = 38, P < 0.001), respectively. Amiloride treatment (1 mM) in the absence of CN- reduced pHi recovery similarly to that caused by CN- (0.34 +/- 0.07, n = 14). CN(-)-treated cells exposed to amiloride demonstrated no additional inhibition (efflux rate 0.65 +/- 0.11, n = 27), suggesting that the inhibition is directed at Na+/H+ exchange. Twenty minutes after CN- removal, CN(-)-treated cells regained their ability to recover from an acid load, thus demonstrating the reversibility of this effect.(ABSTRACT TRUNCATED AT 250 WORDS)