Al-Samir Samer, Kyriazi Despoina, Yool Andrea J, Moser Inês, Kyriazi Kallirroi, Gros Gerolf, Tsiavaliaris Georgios, Endeward Volker
Zentrum Physiologie - 4220, Medizinische Hochschule Hannover, Hannover, Germany.
Institut für Biophysikalische Chemie, Medizinische Hochschule Hannover, Hannover, Germany.
Am J Physiol Cell Physiol. 2025 May 1;328(5):C1605-C1622. doi: 10.1152/ajpcell.00858.2024. Epub 2025 Apr 2.
It has been demonstrated that aquaporin-1 (AQP1), one of the most abundant red cell membrane proteins, constitutes a functionally important channel for CO in red cell membranes. We ask here, whether AQP1 and other gas channel proteins play a role also in red cell oxygen transport. We use a stopped-flow technique to: ) compare the oxygen permeability, [Formula: see text], of AQP1-deficient (Colton Null) with that of normal human red cell membranes, ) compare the [Formula: see text] of with that of normal mouse red cells, ) study the effect of the gas channel inhibitor 4,4'-diisothiocyanato-2,2'-stilbenedisulfonate (DIDS) on [Formula: see text] of human and mouse red cells, and ) investigate all three effects at various temperatures between 7 and 37°C, because O transfer across channels and across membrane lipids may depend differently on temperature. We find that at 7°C/10°C lack of AQP1 in the red cell membrane causes significant reductions of [Formula: see text], by 20% in human and by 37% in mouse red cells. DIDS causes reductions in [Formula: see text] by 34% in human and by 88% in mouse red cells. In addition, the AQP1 inhibitor 5-(phenoxymethyl)furan-2-carbaldehyde (5-PMFC) decreases human red cell [Formula: see text] by ∼40%. All these effects are highly visible at 7°C/10°C, but minor or absent at 25 and 37°C, suggesting that O passage through the channel(s) increases less with temperature than O permeation through membrane lipids. Lack of AQP1 and exposure to DIDS or 5-PMFC indicate that AQP1-possibly along with other gas channels-at <25°C acts as an efficient channel for O. Aquaporin-1 is a membrane protein that conducts CO at 37°C very efficiently. Here, we show that aquaporin-1 also conducts O, but mainly at lower temperatures of around 10°C. Although O transfer across the red cell membrane is accelerated by aquaporin-1 significantly at 10°C, a temperature occurring in poikilotherms, aquaporin-1 apparently does not contribute to O passage at 37°C as it occurs in homoiotherms.
已经证明，水通道蛋白-1（AQP1）是红细胞膜中最丰富的蛋白质之一，它在红细胞膜中构成了一个对一氧化碳具有重要功能的通道。我们在此探讨AQP1和其他气体通道蛋白在红细胞氧气运输中是否也发挥作用。我们使用停流技术来：1）比较缺乏AQP1的（科尔顿阴性）红细胞膜与正常人类红细胞膜的氧渗透性（[公式：见原文]）；2）比较[公式：见原文]与正常小鼠红细胞的[公式：见原文]；3）研究气体通道抑制剂4,4'-二异硫氰酸根合-2,2'-二苯乙烯二磺酸盐（DIDS）对人类和小鼠红细胞[公式：见原文]的影响；4）在7至37°C的不同温度下研究上述所有三种影响，因为氧气通过通道和通过膜脂的转运可能对温度的依赖性不同。我们发现，在7°C/10°C时，红细胞膜中缺乏AQP1会导致[公式：见原文]显著降低，人类红细胞降低20%，小鼠红细胞降低37%。DIDS使人类红细胞的[公式：见原文]降低34%，小鼠红细胞降低88%。此外，AQP1抑制剂5-（苯氧基甲基）呋喃-2-甲醛（5-PMFC）使人类红细胞的[公式：见原文]降低约40%。所有这些影响在7°C/10°C时非常明显，但在25°C和37°C时较小或不存在，这表明氧气通过通道的转运随温度升高的增加幅度小于通过膜脂的渗透。缺乏AQP1以及暴露于DIDS或5-PMFC表明，在<25°C时，AQP1可能与其他气体通道一起作为氧气的有效通道。水通道蛋白-1是一种在37°C时能非常有效地传导一氧化碳的膜蛋白。在此，我们表明水通道蛋白-1也能传导氧气，但主要是在约10°C的较低温度下。尽管在10°C时水通道蛋白-1能显著加速氧气通过红细胞膜的转运，这是变温动物体内出现的温度，但水通道蛋白-1在37°C时显然对氧气通过没有贡献，而37°C是恒温动物体内出现的温度。
