ULTRASTRUCTURAL ALTERATIONS OF THE RED BLOOD CELLS MEMBRANE DURING MECHANICAL CIRCULATION WITH A CENTRIFUGAL PUMP
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概要
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In the mechanism of damage on the red blood cells (RBC) caused by a centrifugal pump, it is not clear about the role of a membrane-skeleton (MS) keeping the membrane-deformability. In this study, we investigated the ultrastrucutural alterations of RBC membrane caused by shear stress, which is assumed to be the major physical factors of hemolysis during mechanical circulation with a centrifugal pump, and focused on band 3 protein (B3) which is one of major proteins in the MS. The analyses were performed with a flow cytometer. In the chronic animal experiment using adult goat after the initiation of left ventricular bypass with a centrifugal pump, their blood samples morphologically showed that the enlarged and bizarre RBC increased, and the density of B3 in the membrane significantly increased with the morphological alterations in chronic phase. The alterations of B3 density and cell shape indicated the ultrastructural disorder in the MS. Therefore the RBC with mechanical circulation were disturbed their membrane and amounts of survived cells showed deformation. For analyzing the mechanism of these damages of RBC membrane, two in vitro tests focused on influence on MS caused by difference of shear rate were preformed. A shear rate of 420 s-1 was loaded for 4 hours to normal goat blood. Another blood samples after homogenizing with estimated shear rate of 104 s-1 were also analyzed. The homogenized samples were destroyed by high shear stress without delay but had no influence on MS of remnant RBC. In contrast, continuous low stress could not break the RBC, and the density of B3 was unchanged in the first 2 hours, however the B3 density increased after 3rd hour. And these affected cells functionally lost their deformability. These results suggested that there are at least two different processes of RBC damage with or without alteration of MS by difference of shear rate. In conclusion, the ultrastructural disorder in the RBC membrane caused by a low shear stress developing in a centrifugal pump and the affected RBC decreased in the membrane-deformability during long circulation with centrifugal pump.
- 日本組織細胞化学会の論文