Permeability of fructose-1,6-bisphosphate in liposomes and cardiac myocytes.
Permeability of fructose-1,6-bisphosphate in liposomes and cardiac myocytes.
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脂质体和心肌细胞中果糖 1,6-二磷酸的渗透性。
DOI：
10.1023/b:mcbi.0000021356.89867.0d
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发表时间：
2004
影响因子：
4.3
通讯作者：
Chien,Sufan
中科院分区：
文献类型：
--
作者：
Wheeler,ThomasJ;McCurdy,JohnM;denDekker,Aaron;Chien,Sufan
果糖-1，6-二磷酸（FBP）有助于在缺血条件下保护心脏和其他器官。以前的研究表明，它可以被各种类型的细胞吸收。在这里，我们扩展了我们小组的观察结果，即FBP可以穿透人工脂质双层并被心肌细胞摄取[8，10]，比较了FBP与L-葡萄糖的摄取。使用通过冻融方法制备的脂质体，FBP进入的速度比L-葡萄糖慢约200倍。对于大豆脂质体或鸡蛋脂质体，50 mM FBP增强了FBP本身的渗透性，对一般渗透性（通过摄取L-葡萄糖测量）影响不大。在21°C离体心肌细胞的实验中，FBP的摄取量超过了L-葡萄糖的摄取量数倍，并在60分钟内达到平衡。在微摩尔水平上有一个饱和组分，在毫摩尔水平上占主导地位的是一个不饱和组分。可饱和组分被Pi和其他磷酸化糖抑制，但亲和力低于FBP。在3°C下也观察到饱和和非饱和吸收。结果表明，FBP进入心肌细胞不是通过简单的渗透通过脂质双层，但通过至少两个不同的蛋白依赖性过程。这种摄取可导致细胞内效应，在低温心脏保存中具有重要意义。
Fructose-1,6-bisphosphate (FBP) helps preserve heart and other organs under ischemic conditions. Previous studies indicated that it can be taken up by various cell types. Here we extended observations from our group that FBP could penetrate artificial lipid bilayers and be taken up by cardiac myocytes [8, 10], comparing the uptake of FBP to that of L-glucose. Using liposomes prepared by the freeze-thaw method, FBP entered about 200-fold slower than L-glucose. For liposomes of either soybean or egg lipids, 50 mM FBP enhanced the permeability of FBP itself, with little effect on general permeability (measured by uptake of L-glucose). In experiments with isolated cardiac myocytes at 21°C, FBP uptake exceeded the uptake of L-glucose by several fold and appeared to equilibrate by 60 min. There was both a saturable component at micromolar levels and a nonsaturable component which dominated at millimolar levels. The saturable component was inhibited by Piand by other phosphorylated sugars, though with lower affinity than FBP. Both saturable and nonsaturable uptakes were also observed at 3°C. The results indicate that FBP enters myocytes not by simple penetration through the lipid bilayer, but via at least two distinct protein-dependent processes. The uptake could lead to intracellular effects important in hypothermic heart preservation.