Rapid Incorporation In Vivo of Intracerebrally Injected 32Pi into Polyphosphoinositides of Three Subfractions of Rat Brain Myelin
Rapid Incorporation In Vivo of Intracerebrally Injected 32Pi into Polyphosphoinositides of Three Subfractions of Rat Brain Myelin
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脑内注射 32Pi 体内快速掺入大鼠脑髓磷脂三个亚组分的多磷酸肌醇
DOI：
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发表时间：
1981
影响因子：
4.7
通讯作者：
H. Brockerhoff
中科院分区：
文献类型：
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作者：
D. S. Deshmukh;S. Kuizon;W. D. Bear;H. Brockerhoff
摘要：在将³²Pᵢ注入大鼠大脑后的1到10分钟间隔内，制备髓磷脂并将其分离为三个亚组分：重、中、轻。然后测定总磷脂和多磷酸肌醇（PPI）的放射性。³²Pᵢ迅速掺入PPI中，在全脑脂质中其放射性占50 - 70%，在髓磷脂脂质中占70%以上。髓磷脂组分将³²Pᵢ掺入回收的总PPI中的量按中＞重＞轻组分的顺序排列；然而，相对比放射性的顺序是重＞轻＞中。在纯化的髓磷脂中，PPI前体磷脂酸（PA）和磷脂酰肌醇（PI）的标记明显低于全脑。重髓磷脂中的二磷酸肌醇（DPI）和三磷酸肌醇（TPI）交换³²Pᵢ的速率比重、轻髓磷脂中的快2到3倍。髓磷脂所有亚组分的DPI交换都比重TPI快得多。结果表明，髓磷脂PPI最活跃的磷酸周转发生在重髓磷脂组分中（可能主要由髓磷脂附属区域组成）。然而，中、轻髓磷脂（最有可能代表紧密排列的髓鞘层）也显示出PPI的快速周转。
Abstract: At intervals ranging from 1 to 10 min after injection of 32Pi into rat brain, myelin was prepared and separated into three subfractions: heavy, medium, and light. The radioactivity of total phospholipids and polyphospho‐inositides (PPI) was then determined. There was rapid incorporation of 32Pi into PPI, which contained 50–70% of the radioactivity among total brain lipids and more than 70% among myelin lipids. The myelin fraction had incorporated 32Pi into total recovered PPI in the order of medium > heavy > light fraction: however, the order of relative specific radioactivities was heavy > light > medium. Labeling of the PPI precursors, phosphatidic acid (PA) and phos‐phatidylinositol (PI), was considerably lower in the purified myelin than in total brain. The di‐ (DPI) and triphosphoinositides (TPI) in heavy myelin exchanged 32Pi at rates 2 to 3 times faster than those in medium and light myelin. DPI of all subfractions of myelin exchanged much faster than TPI. The results show that the most active phosphate turnover of myelin PPI occurs in the heavy myelin fraction (probably largely consisting of myelin appurtenant regions). However, medium and light myelin (most probably representing the closely packed layers of myelin sheaths) also showed rapid turnover of PPI.