Joiner C H, Franco R S, Jiang M, Franco M S, Barker J E, Lux S E
Department of Pediatrics, University of Cincinnati College of Medicine, OH, USA.
Blood. 1995 Dec 1;86(11):4307-14.
Cellular cation homeostasis in mouse erythrocytes with defective membrane skeletons was examined in three mouse mutants, hemolytic anemia (sphha/sphha), spherocytosis (sph/sph), and normoblastosis (nb/nb), and compared with reticulocytes produced by repetitive bleeding of congenic normal mice. To assess reticulocyte maturity, nucleic acid and transferrin receptor contents were measured by fluorescence flow cytometry; mutant cells were somewhat more mature than normal reticulocytes by these criteria. Red blood cell (RBC) sodium contents (Nac+) in homozygous sphha/sphha, sph/sph, and nb/nb animals were 30.1 +/- 0.9, 28.9 +/- 0.3, and 26.9 +/- 1.5 mmol/L cell, respectively, whereas cellular potassium (Kc+) was 102 +/- 2.6, 101 +/- 7.8, and 97.4 +/- 3.0. Nac+ and Kc+ in normal reticulocyte preparations were 11.3 +/- 0.7 and 123 +/- 10, respectively. Net Na+ and K+ fluxes in the presence of ouabain were markedly increased in mutant RBCs. Sodium uptake was 14.8 +/- 1.6, 15.4 +/- 3.3, and 14.7 +/- 3.1 mmol/L cell/h in sphha/sphha, sph/sph, and nb/nb mutants, respectively, whereas K+ loss was 17.0 +/- 4.0, 15.0 +/- 3.8, and 14.1 +/- 2.6. Normal mouse reticulocytes gained Na+ at a rate of 3.9 +/- 1.0 mmol/L cell/h and lost K+ at 6.0 +/- 2.1, rates indistinguishable from those in mature mouse RBCs. Potassium loss from sphha/sphha and nb/nb cells was not dependent on the presence of a Na+ gradient, and net cation movements were insensitive to bumetanide (sphha/sphha and nb/nb RBCs) and to chloride replacement with sulfamate (nb/nb cells). We conclude that mutant mouse RBCs with dysfunctional membrane skeletons have increased passive permeability to monovalent cations. These findings support a role of the membrane skeleton in the maintenance of the membrane permeability barrier and suggest that the abnormal permeability associated with human hereditary spherocytosis and elliptocytosis may be a consequence of the membrane skeleton defects reported in these disorders.
在三种小鼠突变体（溶血性贫血小鼠sphha/sphha、球形红细胞增多症小鼠sph/sph和幼红细胞增多症小鼠nb/nb）中检测了膜骨架有缺陷的小鼠红细胞中的细胞阳离子稳态，并与同基因正常小鼠反复放血产生的网织红细胞进行了比较。为了评估网织红细胞的成熟度，通过荧光流式细胞术测量核酸和转铁蛋白受体含量；根据这些标准，突变细胞比正常网织红细胞稍成熟一些。纯合子sphha/sphha、sph/sph和nb/nb动物的红细胞（RBC）钠含量（Nac+）分别为30.1±0.9、28.9±0.3和26.9±1.5 mmol/L细胞，而细胞钾（Kc+）分别为102±2.6、101±7.8和97.4±3.0。正常网织红细胞制剂中的Nac+和Kc+分别为11.3±0.7和123±10。在哇巴因存在的情况下，突变红细胞中的净Na+和K+通量显著增加。sphha/sphha、sph/sph和nb/nb突变体中钠摄取分别为14.8±1.6、15.4±3.3和14.7±3.1 mmol/L细胞/小时，而K+损失分别为17.0±4.0、15.0±3.8和14.1±2.6。正常小鼠网织红细胞以3.9±1.0 mmol/L细胞/小时的速率摄取Na+，以6.0±2.1的速率损失K+，这些速率与成熟小鼠红细胞中的速率无差异。sphha/sphha和nb/nb细胞的钾损失不依赖于Na+梯度的存在，净阳离子运动对布美他尼（sphha/sphha和nb/nb红细胞）以及用氨基磺酸盐替代氯离子（nb/nb细胞）不敏感。我们得出结论，膜骨架功能失调的突变小鼠红细胞对单价阳离子的被动通透性增加。这些发现支持了膜骨架在维持膜通透性屏障中的作用，并表明与人类遗传性球形红细胞增多症和椭圆形红细胞增多症相关的异常通透性可能是这些疾病中报道的膜骨架缺陷的结果。
