Blastocoel expansion in the preimplantation mouse embryo: role of extracellular sodium and chloride and possible apical routes of their entry.
Blastocoel expansion in the preimplantation mouse embryo: role of extracellular sodium and chloride and possible apical routes of their entry.
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DOI：
10.1016/0012-1606(89)90312-6
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发表时间：
1989-05
影响因子：
2.7
通讯作者：
F. Manejwala;E. Cragoe;R. Schultz
中科院分区：
文献类型：
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作者：
F. Manejwala;E. Cragoe;R. Schultz
小鼠囊胚的滋养外胚层是一种液体运输上皮，负责产生一个充满液体的腔，称为囊胚腔。离子从培养基向囊胚腔的矢量运输产生渗透梯度，驱动液体穿过该上皮。我们在这里报告说，在培养基中取代Na+或Cl−，而不是K+，使小鼠囊胚的囊胚腔扩张率减半。进入滋养外胚层的Na+可能涉及几种途径，因为在高度特异性的Na+ H+交换抑制剂5-（N-乙基-N-异丙基）阿米洛利的存在下，囊胚腔扩张和22 Na+摄取均降低，而阿米洛利敏感性Na+通道阻滞剂苯扎明的作用程度较小。22 Na+的摄取表现出饱和动力学，作为细胞外Na+浓度的函数，而36 Cl−的摄取是线性的。此外，无论是Cl− HCO− 3交换器的抑制剂4，4-二异硫氰基芪-2，2-二磺酸，还是Cl−阻断剂2-（3，4-二氯苄基）-5-硝基苯甲酸，都不会影响囊胚腔扩张或36 Cl−摄取。这些结果表明，Na+进入小鼠囊胚载体介导的，可能涉及几个途径，包括Na+ H+交换器和可能的Na+通道。然而，氯离子进入可能不是载体介导的，可能通过细胞旁途径发生，即在滋养外胚层细胞之间。
The trophectoderm of the mouse blastocyst is a fluid transporting epithelium that is responsible for generating a fluid-filled cavity called the blastocoel. Vectorial transport of ions from the medium into the blastocoel generates an osmotic gradient that drives fluid across this epithelium. We report here that substitution of Na+ or Cl−, but not K+, in the medium halves the rate of blastocoel expansion in the mouse blastocyst. Entrance of Na+ into the trophectoderm may involve several routes, since both blastocoel expansion and 22 Na+ uptake are decreased in the presence of the highly specific Na+ H+ exchanger inhibitor, 5-(N-ethyl-N-isopropyl) amiloride, and to a lesser extent with the amiloride-sensit Na+-channel blocker, benzamil. Uptake of 22 Na+ manifests saturation kinetics as a function of extracellular Na+ concentration, whereas uptake of 36 Cl− is linear. Furthermore, neither 4, 4-diisothiocyanostilbene-2, 2-disulfonic acid, which is an inhibitor of the Cl− HCO− 3 exchanger, nor 2-(3, 4-dichlorobenzyl)-5-nitrobenzoic acid, which is a Cl−-blocker, affect either blastocoel expansion or 36 Cl− uptake. These results suggest that Na+ entry into the mouse blastocyst is carrier-mediated and probably involves several routes that include the Na+ H+ exchanger and possibly the Na+-channel. Chloride entry, however, may not be carrier-mediated and may occur through a paracellular route, ie, between the trophectodermal cells.