Evidence that aquaporin 1 is a major pathway for CO2 transport across the human erythrocyte membrane
Evidence that aquaporin 1 is a major pathway for CO2 transport across the human erythrocyte membrane
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DOI：
10.1096/fj.04-3300com
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发表时间：
2006-10-01
期刊：
影响因子：
4.8
通讯作者：
Gros, G.
中科院分区：
文献类型：
--
作者：
Endeward, V.;Musa-Aziz, R.;Gros, G.
我们在这里报告的应用程序，以前描述的方法，直接确定的CO2渗透性（P-CO2）的正常人红细胞（RBC）与那些缺乏水通道蛋白1（AQP 1），以及AQP 1表达非洲爪蟾卵母细胞的细胞膜。该方法测量细胞悬浮液中CO2、HCO 3-和H2O之间的O-18交换。此外，我们测量了碱性表面pH值（pH（S））瞬变所造成的优势效应进入的CO2与HCO 3-进入卵母细胞暴露于步骤增加[CO2]。我们报告1）AQP 1构成了人红细胞中分子CO2的主要途径;缺乏AQP 1使P-CO2从正常值0.15 +/- 0.08（SD; n = 85）cm/s降低60%至0.06 cm/s。AQP 1在卵母细胞中的表达使P-CO2增加2倍，使碱性pHS梯度加倍。2)pCMBS是AQP 1水通道的抑制剂，仅通过作用于AQP 1来降低RBC的P-CO2，因为它对AQP 1缺陷型RBC没有影响。3)RBC的P-CO2测定和卵母细胞的pH（S）测量表明，DIDS将AQP 1的CO2途径抑制一半。4)红细胞至少有一个其他的DIDS敏感途径的CO2。我们的结论是，AQP 1是负责60%的高P-CO2的红细胞和另一个，到目前为止，身份不明，CO2途径存在于这个膜，可能占至少30%的总P-CO2。
We report here the application of a previously described method to directly determine the CO2 permeability (P-CO2) of the cell membranes of normal human red blood cells (RBCs) vs. those deficient in aquaporin 1 (AQP1), as well as AQP1-expressing Xenopus laevis oocytes. This method measures the exchange of O-18 between CO2, HCO3-, and H2O in cell suspensions. In addition, we measure the alkaline surface pH (pH(S)) transients caused by the dominant effect of entry of CO2 vs. HCO3- into oocytes exposed to step increases in [CO2]. We report that 1) AQP1 constitutes the major pathway for molecular CO2 in human RBCs; lack of AQP1 reduces P-CO2 from the normal value of 0.15 +/- 0.08 (SD; n = 85) cm/s by 60% to 0.06 cm/s. Expression of AQP1 in oocytes increases P-CO2 2-fold and doubles the alkaline pHS gradient. 2) pCMBS, an inhibitor of the AQP1 water channel, reduces P-CO2 of RBCs solely by action on AQP1 as it has no effect in AQP1-deficient RBCs. 3) P-CO2 determinations of RBCs and pH(S) measurements of oocytes indicate that DIDS inhibits the CO2 pathway of AQP1 by half. 4) RBCs have at least one other DIDS-sensitive pathway for CO2. We conclude that AQP1 is responsible for 60% of the high P-CO2 of red cells and that another, so far unidentified, CO2 pathway is present in this membrane that may account for at least 30% of total P-CO2.