SUBCELLULAR CHARACTERISTICS OF PHOSPHOLIPASE-A2 ACTIVITY IN THE RAT-KIDNEY - ENHANCED CYTOSOLIC, MITOCHONDRIAL, AND MICROSOMAL PHOSPHOLIPASE-A2 ENZYMATIC-ACTIVITY AFTER RENAL ISCHEMIA AND REPERFUSION
SUBCELLULAR CHARACTERISTICS OF PHOSPHOLIPASE-A2 ACTIVITY IN THE RAT-KIDNEY - ENHANCED CYTOSOLIC, MITOCHONDRIAL, AND MICROSOMAL PHOSPHOLIPASE-A2 ENZYMATIC-ACTIVITY AFTER RENAL ISCHEMIA AND REPERFUSION
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DOI：
10.1172/jci115202
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发表时间：
1991-05-01
影响因子：
15.9
通讯作者：
BONVENTRE, JV
中科院分区：
文献类型：
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作者：
NAKAMURA, H;NEMENOFF, RA;BONVENTRE, JV
磷脂酶A2（PLA 2）的活动在细胞溶质，线粒体和微粒体组分的大鼠肾脏的特点是在控制条件下，缺血后，随后缺血和再灌注。 两种形式的PLA 2活性存在于胞质组分中：高分子量形式，对磷脂酰胆碱（PC）和磷脂酰乙醇胺（PE）有活性，纯化后分子量为110 kD;和较小的形式（M（r）几乎等于14 kD），对PE有活性。 在线粒体和微粒体组分中，对PC和PE都有活性的单一形式（M（r）几乎等于14 kD）占主导地位。 在pH 8.5-9.5时，各组分的活性最佳。 当Ca ~（2+）浓度（[Ca ~（2+）]）在10 ~（-7）~ 10 ~（-6）M范围内增加时，胞浆中的PLA_2活性增强。 线粒体PLA 2活性需要较高的[Ca ~（2+）]（> 10 ~（-6）M）才能激活，缺血45分钟后胞浆PLA 2活性下降，而线粒体和微粒体活性升高。 当缺血再灌注1小时，细胞溶质，线粒体和微粒体的活动增强。 单独缺血不改变PLA 2活性的凝胶过滤色谱图，但缺血和再灌注导致在胞质和线粒体组分中出现新的活性峰（M（r）几乎等于2-3 kD）。因此，大鼠肾脏具有多种形式的PLA 2活性，可能代表不同的酶，具有Ca 2+依赖性，表明在体内受Ca 2+调节。 缺血和再灌注导致各亚细胞组分中PLA 2活性的稳定增加，这可能与PLA 2的共价修饰有关，这可能是膜磷脂降解的原因，并增加了不饱和游离脂肪酸的组织水平。
Phospholipase A2 (PLA2) activities in cytosolic, mitochondrial, and microsomal fractions of rat kidneys were characterized under control conditions, after ischemia, and subsequent to ischemia and reperfusion. Two forms of PLA2 activity were present in the cytosolic fraction: a high molecular weight form, active against phosphatidylcholine (PC), and phosphatidylethanolamine (PE), which upon purification has a molecular mass of 110 kD; and a smaller form (M(r) almost-equal-to 14 kD), active against PE. In mitochondrial and microsomal fractions a single form (M(r) almost-equal-to 14 kD), active against both PC and PE, was dominant. Activities in each fraction were optimal at pH 8.5-9.5. Cytosolic PLA2 activity was enhanced when Ca2+ concentration ([Ca2+]) was increased over the range of 10(-7) to 10(-6) M. Mitochondrial PLA2 activity required higher [Ca2+] for activation (> 10(-6) M).After 45 min of ischemia cytosolic PLA2 activity was decreased, whereas mitochondrial and microsomal activities were increased. When ischemia was followed by 1 h of reperfusion, cytosolic, mitochondrial and microsomal activities were enhanced. Ischemia alone did not change the gel filtration chromatography patterns of PLA2 activity, but ischemia and reperfusion resulted in the appearance of a new peak of activity in cytosolic and mitochondrial fractions (M(r) almost-equal-to 2-3 kD).Thus, the rat kidney has multiple forms of PLA, activity, likely representing distinct enzymes, with Ca2+ dependencies suggesting regulation by Ca2+ in vivo. Ischemia and reperfusion result in stable increases of PLA2 activity in each subcellular fraction, perhaps related to covalent modifications of PLA2's, which likely account for membrane phospholipid degradation, and increased tissue levels of unsaturated free fatty acids.