A NUTRIENT-PERMEABLE CHANNEL ON THE INTRAERYTHROCYTIC MALARIA PARASITE
A NUTRIENT-PERMEABLE CHANNEL ON THE INTRAERYTHROCYTIC MALARIA PARASITE
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DOI：
10.1038/362643a0
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发表时间：
1993-04-15
期刊：
影响因子：
64.8
通讯作者：
MCCLESKEY, EW
中科院分区：
文献类型：
--
作者：
DESAI, SA;KROGSTAD, DJ;MCCLESKEY, EW
在红细胞内的48小时循环中，人类疟疾寄生虫恶性疟原虫的体积增加了25倍，并进行无性分裂。这种快速生长需要大量的营养物质，这一问题因宿主红细胞的较低代谢率和相对离子不渗透性而加剧。小营养物质直接穿过将寄生虫与红细胞胞质分离的两层膜可能对寄生虫发育很重要，并已被放射性标记的葡萄糖2，氨基酸3，4和嘌呤核苷4 -6证明。然而，疟原虫的通量研究仅限于无红细胞寄生虫的悬浮液，因此不能用于检查所涉及的两种膜的单独运输特性。在这里，我们使用细胞贴附膜片钳方法7来克服这一限制。在去除介入的红细胞膜并在小（3-5妈妈）寄生虫上形成千兆欧姆密封后，我们研究了穿过寄生虫空泡膜（PVM）的运输，PVM是将寄生虫与红细胞胞质分离的两种膜的外部。一个140 pS的通道，这是可渗透的阳离子和阴离子的PVM上确定。该通道以高密度存在，在PVM的静息电位下98%以上的时间是开放的，并且对赖氨酸和葡萄糖醛酸是可渗透的。该通道可以很容易地运输氨基酸和单糖穿过PVM，并且可能是满足寄生虫代谢需求所必需的。
DURING its 48-hour cycle inside the red blood cell, the human malaria parasite, Plasmodium falciparum, increases its volume 25-fold and divides asexually. This rapid growth demands large amounts of nutrients, a problem exacerbated by the lower metabolic rate and relative ionic impermeability of the host red blood cell. Direct passage of small nutrients across the two membranes that separate the parasite from the erythrocyte cytosol may be important for parasite development, and has been demonstrated for radiolabelled glucose2, amino acids3,4 and purine nucleosides4-6. Flux studies on plasmodia are limited, however, to suspensions of erythrocyte-free parasites and so cannot be used to examine the individual transport properties of the two membranes involved. Here we use the cell-attached patch clamp method7 to overcome this limitation. After removing the intervening red blood cell membrane and forming gigaohm seals on the small (3-5 mum) parasite, we studied transport across the parasitophorous vacuole membrane (PVM), the outer of the two membranes that separate the parasite from the erythrocyte cytosol. A 140-pS channel which is permeable to both cations and anions was identified on the PVM. This channel is present at high density, is open more than 98 per cent of the time at the resting potential of the PVM, and is permeable to lysine and glucuronate. The channel can readily transport amino acids and monosaccharides across the PVM and may be essential for fulfilling the parasite's metabolic demands.