Shiga T, Sekiya M, Maeda N, Kon K, Okazaki M
Biochim Biophys Acta. 1985 Apr 11;814(2):289-99. doi: 10.1016/0005-2736(85)90447-x.
The deformability of human erythrocytes was measured in a rheoscope, as a function of intracellular calcium content (varied with ionophore (A23187) and CaCl2) without complete ATP depletion and echinocytic transformation. Loading calcium into intact erythrocytes (calcium content: 16.8 mumol/1 packed cells = 1.48 amol per cell), the cell volume and energy charge gradually decreased. Further, the membrane fluidity of the lipid portion decreased without crosslinking of membrane proteins. A distinct transition from deformable to undeformable cells was observed by the rheoscope technique: i.e., 50% transition occurred at 40-50 mumol calcium/1 packed cells (= 3.5-4.0 amol per cell) and more than 90% above 100 mumol/1 packed cells (= 6.5 amol per cell) at a shear stress of 140 dyn/cm2. The deformable cells maintained their deformability to ellipsoidal disks independent of the average calcium content. The underformable cells, separated as high-density cells by density gradient centrifugation after calcium-loading, showed lower glucose-6-phosphate dehydrogenase activity than low-density-deformable cells; thus, the calcium-loaded, undeformable cells were presumably in vivo aged cells. The younger cells, fractionated as low-density cells from intact erythrocytes, were more deformable than aged cells. Upon calcium-loading, the younger cells restored their cell volume and deformability, while the aged cells, containing originally more calcium and less ATP, decreased their volume and became undeformable. Therefore, calcium accumulation by ionophore-CaCl2 takes place in preference to aged cells of lower energy metabolism, and leads to cellular dehydration and loss of deformability, due to condensed hemoglobin and altered membrane organization.
在流变仪中测量人红细胞的变形能力，该能力是细胞内钙含量（通过离子载体（A23187）和氯化钙改变）的函数，且未完全耗尽ATP和发生棘红细胞转化。将钙加载到完整红细胞中（钙含量：16.8 μmol/1 packed cells = 1.48 amol/细胞），细胞体积和能量电荷逐渐降低。此外，脂质部分的膜流动性降低，而膜蛋白未发生交联。通过流变仪技术观察到从可变形细胞到不可变形细胞的明显转变：即在140 dyn/cm² 的剪切应力下，50% 的转变发生在40 - 50 μmol钙/1 packed cells（= 3.5 - 4.0 amol/细胞）时，而在100 μmol/1 packed cells（= 6.5 amol/细胞）以上时超过90%。可变形细胞保持其对椭圆形盘状的变形能力，与平均钙含量无关。加载钙后通过密度梯度离心分离为高密度细胞的不可变形细胞，其葡萄糖-6-磷酸脱氢酶活性低于低密度可变形细胞；因此，加载钙的不可变形细胞可能是体内衰老细胞。从完整红细胞中分离为低密度细胞的较年轻细胞比衰老细胞更易变形。加载钙后，较年轻细胞恢复其细胞体积和变形能力，而原本钙含量较高且ATP较少的衰老细胞体积减小并变得不可变形。因此，离子载体 - 氯化钙介导的钙积累优先发生在能量代谢较低的衰老细胞中，并导致细胞脱水和变形能力丧失，这是由于血红蛋白浓缩和膜组织改变所致。
