Engström K G, Meiselman H J
Department of Cardiothoracic Surgery, University Hospital of Northern Sweden, Umeå, Sweden.
Cytometry. 1996 Jan 1;23(1):22-7. doi: 10.1002/(SICI)1097-0320(19960101)23:1<22::AID-CYTO4>3.0.CO;2-O.
Micropipette aspiration is a potentially useful and accurate technique to measure red blood cell (RBC) geometry. Individual RBCs are partially aspirated and from the resulting sphere diameter, total cell length, and pipette diameter, membrane area and cell volume can be calculated. In this study we have focused on possible shape artifacts associated with the aspirated portion of RBC. We observed that the apparent RBC geometry (calculated area and volume) changed markedly (P < 0.001) with the applied aspiration pressure; for normal human RBC the area increased by 5.6 +/- 0.6% and volume decreased by 4.7 +/- 0.6% when the aspiration pressure was increased from 20 to 100 mm water. The calculated membrane area dilation modulus was 7.4 dyn/ cm, which is far below the expected value, and microscopic observations revealed a membrane folding artifact as a possible artifact. These assumptions were strengthened by using a short-duration (3 s) pressure peak of 20-100-20 mm water. The folding then disappeared permanently, but a small (0.31 +/- 0.09%; P < 0.001) area decrease was detected which yields a realistic dilation modulus of 215 dyn/cm. We conclude that membrane folding can critically affect RBC micropipette measurements and that a transient pressure peak can unfold the RBC membrane, thus allowing accurate measurements of RBC geometry.
微量移液器抽吸法是一种测量红细胞（RBC）几何形状的潜在有用且准确的技术。将单个红细胞部分抽吸，根据所得球体直径、细胞总长度和移液器直径，可以计算出膜面积和细胞体积。在本研究中，我们重点关注了与红细胞抽吸部分相关的可能的形状伪影。我们观察到，随着施加的抽吸压力的变化，红细胞的表观几何形状（计算出的面积和体积）发生了显著变化（P < 0.001）；对于正常人类红细胞，当抽吸压力从20毫米水柱增加到100毫米水柱时，面积增加了5.6±0.6%，体积减少了4.7±0.6%。计算出的膜面积扩张模量为7.4达因/厘米，远低于预期值，显微镜观察显示膜折叠伪影可能是一种伪影。使用20 - 100 - 20毫米水柱的短持续时间（3秒）压力峰值强化了这些假设。然后折叠永久消失，但检测到有一个小的（0.31±0.09%；P < 0.001）面积减小，这产生了一个实际的扩张模量为215达因/厘米。我们得出结论，膜折叠会严重影响红细胞微量移液器测量，而短暂压力峰值可以展开红细胞膜，从而实现对红细胞几何形状的准确测量。
